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J. Biol. Chem., Vol. 280, Issue 17, 17520-17525, April 29, 2005

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Paradoxical Inhibition of Protein Aggregation and Precipitation by Transglutaminase-catalyzed Intermolecular Cross-linking^*

Takashi Konno, Takashi Morii¶, Hirofumi Shimizu, Shigetoshi Oiki, and Koji Ikura||

From the Department of Molecular Physiology and Biophysics, Faculty of Medical Sciences, University of Fukui, Matsuoka, Yoshida, Fukui, 910-1193, Japan, ^¶Institute of Advanced Energy, Kyoto University, Gokasho, Uji, 611-0011, Japan, and ^||Department of Applied Biology, Faculty of Textile Science, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, 606-8585, Japan

Received for publication, December 13, 2004 , and in revised form, February 18, 2005.

	ABSTRACT

TOP ABSTRACT INTRODUCTION EXPERIMENTAL PROCEDURES RESULTS DISCUSSION REFERENCES

 
Cross-linking of proteins catalyzed by tissue transglutaminase has been suggested to play key roles in a variety of cellular events, including cell apoptosis and human pathogenesis (e.g. polyglutamine and Alzheimer diseases). It has often been suggested that tissue transglutaminase enhances aggregation and precipitation of damaged or pathogenic proteins. To ascertain whether this is accurate, we investigated the effects of tissue transglutaminase-catalyzed modulation on the aggregation of structurally damaged and unfolded proteins. Our results indicated that the aggregation and precipitation of some unfolded proteins were inhibited by transglutaminasecatalyzed reaction, although the effect was strongly dependent upon the target protein species. To elucidate the molecular events underlying the inhibitory effect, extensive analysis was performed with regard to reduced -lactoglobulin using a number of techniques, including chromatography and spectroscopy. The results indicated that cross-linking yields high molecular weight soluble polymers but inhibits the growth of insoluble aggregates. The cross-linked -lactoglobulin retained stable secondary structures with a hydrophobic core. We concluded that the transglutaminase-catalyzed intermolecular cross-linking did not necessarily enhance protein aggregation but could sometimes have a suppressive effect. The results of the present study suggested that tissue transglutaminase modifies aggregation and deposition of damaged or pathogenic proteins in vivo in a wide variety of manners depending on the target protein species and solution conditions.

	INTRODUCTION

TOP ABSTRACT INTRODUCTION EXPERIMENTAL PROCEDURES RESULTS DISCUSSION REFERENCES

 
Protein clustering occurs in the highly concentrated intra- and extracellular solutions of the living body (1, 2). Fine balancing of the intermolecular forces of proteins in biological fluids may realize a variety of physical states, such as dispersed, equilibrium clustered, glass-like, or crystal states, as in pure solutions (3–7), because biological environments are highly diverse. Investigation of the factors that affect the intermolecular interactions of proteins are of primary importance from a biological viewpoint. Such information is also essential for clinical control of abnormal protein aggregation, such as amyloid formation in patients with neurodegenerative diseases (8–12).

Biological protein assembly is mediated not only by noncovalent interactions but also by covalent cross-linking catalyzed by enzymes. The most important group of cross-linking enzymes is the transglutaminase (TG)¹ family (13–15). TG are thiol- and Ca²⁺-dependent acyl transferases that catalyze formation of amide bonds between the -carboxamide groups of peptide-bound glutamine residues and the primary amino groups of various compounds, including the -amino group of lysine in proteins. It is commonly held that covalent cross-linking of protein molecules always enhances protein aggregation and precipitation. In fact, cross-linking by TG stabilizes blood clots and skin keratin under physiological conditions (13, 15). Tissue-type transglutaminase (tTG) is also a candidate for the factor that induces formation of neuronal inclusions in the brains of patients with human diseases, such as the polyglutamine and Alzheimer diseases (16–19).

However, we have recently demonstrated that the cross-linking reaction catalyzed by tTG does not always enhance protein aggregation; the cross-linking reaction in the intramolecular mode was shown to strongly suppress the aggregation of disease-related proteins (20). This led to the question of whether the intermolecular mode of cross-linking would also suppress protein aggregation. In fact, Lai et al. (21) recently reported that tTG-catalyzed intermolecular cross-linking of a polyglutamine-containing protein formed high molecular weight soluble polymers, but inhibited precipitation. An accurate answer to this question must be pursued, as the tTG-catalyzed cross-linking has been suggested to play key roles in a variety of cellular events, including regulation of cellular growth, differentiation, apoptosis, and human pathogenesis (14, 22).

In the present study, we examined whether the intermolecular cross-linking of damaged and structurally unfolded proteins enhances or inhibits their aggregation and precipitation. To assess this problem from a general viewpoint, we examined four structurally unrelated proteins as substrates of tTG: bovine -lactoglobulin A (LG; -sheet-type), bovine serum albumin (BSA; -helix-type), human -lactalbumin (LA; /-type), and bovine -casein (natively unfolded type). LG, LA, and BSA were unfolded by reducing the disulfide bonds, which might be the simplest model for biological protein damage. First, we performed simple aggregation and cross-linking analysis of all the proteins. This was followed by extensive analysis for LG as a typical case using biochemical and biophysical techniques.

	EXPERIMENTAL PROCEDURES

TOP ABSTRACT INTRODUCTION EXPERIMENTAL PROCEDURES RESULTS DISCUSSION REFERENCES

 
Materials—Guinea pig liver transglutaminase was purified on an immunoadsorbent column as described previously (23). LG, LA, BSA, bovine -casein, and bovine -chymotrypsin were purchased from Sigma-Aldrich and were used without further purification. Other chemicals of reagent grade were purchased from Nacalai Tesque Co. (Kyoto, Japan).

Aggregation and Cross-linking Reactions—All of the sample solutions were prepared in 10 mM Tris (pH 7.5), and the pH was adjusted carefully with small amounts of HCl. Non-covalent aggregation of LG, BSA, and LA was initiated by adding 10 mM dithiothreitol (DTT) and 5 mM CaCl₂ at 37 °C. The tTG-catalyzed cross-linking reaction was initiated by adding 130, 260, or 650 nM tTG, 10 mM DTT, and 5 mM CaCl₂ at 37 °C. Irreversibly inactivated tTG used for control experiments was prepared by heat treatment of tTG at 70 °C for 5 min. A reference experiment under reducing conditions without aggregation and cross-linking of LG was performed in a solution containing 10 mM DTT and 1 mM EDTA. SDS-PAGE analysis was performed by the standard method of Laemmli (24) with densitometric measurement of the Coomassie Brilliant Blue-stained gel. Solution turbidity was measured by absorbance at 320 nm using a U-3300 spectrometer (Hitachi, Tokyo).

In the experiments using -casein, the protein was dissolved in 10 mM Tris (pH 7.5), 5 mM CaCl₂, and 10 mM DTT and incubated at 37 °C for 24 h. At this time point, tTG was added to the solution, and then the turbidity was monitored.

Size-exclusion Gel Chromatography and Microfiltration—Analytical size-exclusion gel chromatography (SEC) was performed using the Class M10A HPLC system (Shimadzu, Kyoto, Japan) equipped with a G3000SW column (Tosoh, Tokyo). The equilibrium and elution buffers were 0.1 M sodium phosphate buffer (pH 7.5), and the flow rate was 1 ml/min. Absorbance at 280 nm was monitored. The samples loaded onto SEC (20 µl) were pretreated by microfiltration with an Ultrafree-MC filter (pore size, 0.22 µm; Millipore Co., Bedford, MA).

Spectroscopic Measurements—Circular dichroism (CD) spectra were measured with a Jasco J-820 spectropolarimeter (Jasco, Tokyo) using a quartz cell with a path length of 0.5 or 1 mm. The protein concentrations were 6 and 150 µM for far- and near-UV measurements, respectively. The temperature of the cell was controlled using a Peltier-type PTC-423S apparatus (Jasco).

Phase Separation of LG Solutions in the Presence of CaCl₂—The cross-linked samples were prepared in advance by adding 650 nM tTG and 5 mM CaCl₂ to the reduced reference sample followed by incubation at 37 °C for 24 h. The reduced reference and cross-linked samples containing 100 µM LG and various concentrations of CaCl₂ were incubated at 37 °C for 24 h. The samples after incubation were subjected to microfiltration (pore size, 0.22 µm), and the protein concentration of the supernatant was determined by averaging estimates obtained from absorbance at 280 nm and the BCA method. The concentrations of CaCl₂ in the presence of 1 mM EDTA were determined by the method of Goldstein (25).

Proteolytic Digestion Experiments—The reaction mixtures containing 270 µM LG and 10 mM DTT were used for the digestion experiments monitored by SDS-PAGE. Depending on the sample species, 650 nM tTG, 5 mM CaCl₂, or 1 mM EDTA was added to the solutions. The mixtures were incubated at 37 °C for 24 h. Then, -chymotrypsin was added at a final concentration of 10 µg/ml, and the mixtures were incubated at 25 °C with stirring.

	RESULTS

TOP ABSTRACT INTRODUCTION EXPERIMENTAL PROCEDURES RESULTS DISCUSSION REFERENCES

 
tTG-catalyzed Suppression of Non-covalent Protein Aggregation and Precipitation—Structurally damaged and unfolded protein molecules have a strong tendency to form aggregates because exposure of hydrophobic parts of the protein interior to the aqueous environment enhances the intermolecular hydrophobic interactions that overcome electrostatic or other types of intermolecular repulsion. Accordingly, we expected that reduction of disulfide bonds and the subsequent unfolding of proteins would also induce their non-covalent aggregation in a medium of relatively high ionic strength that partially shields electrostatic repulsion. This type of aggregation and precipitation was actually observed for LG, LA, and BSA at neutral pH at 37 °C in the presence of DTT and Ca²⁺ (Fig. 1, A–C, star symbols). Aggregation of the reduced LG was suppressed completely by chelation of trace ions by EDTA (Fig. 1A, filled circles). This sample containing highly reduced LG without any aggregates in the presence of 1 mM EDTA is referred to as the "reduced reference" sample throughout this report. Addition of an excess amount of CaCl₂ (e.g. 5 mM) to this reduced reference solution strongly induced non-covalent aggregation and precipitation of LG (Fig. 1D, star symbols).

View larger version (34K): [in this window] [in a new window]   FIG. 1. tTG-catalyzed inhibition of protein aggregation. A–C, turbidity changes of protein solutions in the presence of tTG at 37 °C. Protein species in the solutions were 270 µM LG (A), 30 µM BSA (B), and 70 µM LA (C). The concentrations of tTG were 0 (* , •), 130 (), 260 (), and 650 () nM. All of the solutions contained 10 mM Tris (pH 7.5) and 10 mM DTT. They also contained 5 mM CaCl2 except for the sample indicated by (•) in A, which contained no CaCl2 and 1 mM EDTA. D, turbidity change of reduced LG solution (100 µM) induced by addition of 5 mM CaCl2. The solution also contained 0 (*) or 650 nM tTG (). The reduced sample solution was prepared in advance by incubating LG in the presence of 10 mM Tris (pH 7.5), 10 mM DTT, and 1 mM EDTA at 37 °C for 24 h.

View larger version (22K): [in this window] [in a new window]   FIG. 2. Turbidity changes of -casein solution. -Casein was dissolved in 10 mM Tris (pH 7.5), 5 mM CaCl2, and 10 mM DTT and incubated at 37 °C for 24 h. At this time point, tTG was added at a concentration of 0 (•) or 260 nM (). The solution turbidity was monitored by determining the absorbance at 320 nm.

View larger version (23K): [in this window] [in a new window]   FIG. 3. Solubility of reduced LGs as a function of [CaCl2]. Concentrations of the reduced reference (•) and cross-linked LGs () in the solution phase were determined after incubation at 37 °C for 24 h. The horizontal axis is represented on a logarithmic scale. See "Experimental Procedures" for details.

View larger version (22K): [in this window] [in a new window]   FIG. 4. tTG-catalyzed cross-linking of LG monitored by SDS-PAGE. The LG solution at a concentration of 270 µM contained 10 mM Tris (pH 7.5), 10 mM DTT, 5 mM CaCl2, and 650 nM tTG and was incubated at 37 °C for 0, 1, 3, 5, 6.5, or 24 h. Arrows 1 and 3 indicate monomeric and highly polymerized LGs, respectively. Arrow 2 indicates the position of tTG.

View larger version (39K): [in this window] [in a new window]   FIG. 5. Size-exclusion gel chromatography of LG in the aggregation and cross-linking processes. A, typical chromatograms for the sample without aggregation at 0 time (top panel) and the aggregated samples after a 5-h incubation at 37 °C in the presence of 10 mM DTT, 5 mM CaCl2, and 0 nM (middle panel) or 650 nM tTG (bottom panel). B and C, fractional changes of three populations of LG for the samples containing 0 (B) or 650 nM tTG (C). , non-aggregated N group; •, aggregates of <0.22 µm, S group; *, aggregates of >0.22 µm, L group.

In contrast, in the presence of tTG and CaCl₂, the L fraction did not increase substantially, whereas the S fraction increased rapidly (Fig. 5C). In this case, essentially all the molecules were trapped in the S group after incubation for 24 h (Fig. 6, open symbols). These results indicated that reduced LG modified by tTG could not grow to form large aggregates. The half-decay time constant () of the N fraction of the tTG-containing sample was 4.2 ± 0.2 h (Figs. 5C and 6, open symbols). These decay kinetics were similar to those observed for the decay of the monomer fraction determined by SDS-PAGE analysis (Fig. 6, filled symbols). Both decays advanced at the same rate in the initial 4 h of incubation, indicating that growth of the S fraction in the presence of tTG could be explained completely by the cross-linking reaction at the early stages. The cross-linked high molecular weight LG was trapped in the solution phase. At later stages of incubation, the decay of the N fraction of SEC was slightly faster than that of the monomer fraction on SDS-PAGE (Fig. 6), suggesting a minor contribution of non-covalent mechanisms for the later assembly process of LG.

View larger version (21K): [in this window] [in a new window]   FIG. 6. Kinetic changes in the monomer components in the presence of 650 nM tTG. The fraction of the N group monitored by SEC () and the monomer fraction monitored by SDS-PAGE (•) of cross-linked LG. The solution contained 270 µM LG, 650 nM tTG, 10 mM DTT, and 5 mM CaCl2 and was incubated at 37 °C.

Conformational Changes of LG Accompanied by Cross-linking—The conformational changes of LG accompanying reduction and cross-linking were analyzed by CD spectroscopy. The spectrum in the near-UV region of the reduced reference LG showed a total loss of tertiary structures by incubation at 37 °C for 24 h (Fig. 7A, thick solid line). The decrease in ellipticity at 206 nm of the far-UV CD spectrum also demonstrated unfolding of secondary structures by reduction (Fig. 7A, thick solid line). The near-UV CD spectrum of LG in the presence of tTG and Ca²⁺ indicated that the cross-linking reaction did not inhibit the breakdown of the tertiary structures (Fig. 7B, broken line). However, unfolding of the secondary structures was partly blocked by cross-linking (compare the broken and thick solid lines in Fig. 7B). The addition of tTG and CaCl₂ to the fully reduced reference sample also resulted in significant recovery of the shape of the far-UV CD spectra (Fig. 7C). The spectral shape of the cross-linked LG shown in Fig. 7C was quite similar to that shown in Fig. 7B.

View larger version (22K): [in this window] [in a new window]   FIG. 7. CD spectra of LGs. A, near-UV CD spectra of the samples incubated at 37 °C for 24 h in the presence of 10 mM DTT. Thick solid lines, 1 mM EDTA. Broken lines, 5 mM CaCl2 and 650 nM tTG. The spectrum of native LG without reduction is also presented for comparison (thin solid line). B, far-UV CD spectra. The sample species were the same as those in A. C, far-UV CD spectra of reduced LG with and without tTG-catalyzed cross-linking. Thick solid line, without cross-linking. Broken line, cross-linked. In this case, the reduced samples were prepared in advance by incubation of LG (100 µM) in the presence of 10 mM Tris (pH 7.5), 10 mM DTT, and 1 mM EDTA at 37 °C for 24 h. Then, the cross-linked sample, prepared by adding 5 mM CaCl2 and 650 nM tTG to this highly reduced sample, was further incubated at 37 °C for 12 h.

View larger version (20K): [in this window] [in a new window]   FIG. 8. Kinetic changes in []293 (A) and []206 (B). LG solution (270 µM) was incubated at 37 °C under reducing conditions. •, 1 mM EDTA and no tTG. , 5 mM CaCl2 and 650 nM tTG.

View larger version (23K): [in this window] [in a new window]   FIG. 9. Stability of residual structures of reduced LGs. A and B, cooling-induced changes in the far-UV CD spectra of the reduced reference (A) and cross-linked LG (B). The reduced reference sample (270 µM LG) was prepared in 10 mM DTT and 1 mM EDTA at 37 °C for 24 h. The cross-linked sample (270 µM LG) was prepared in 10 mM DTT, 5 mM CaCl2, and 650 nM tTG at 37 °C for 24 h. The spectra were measured at 25 °C (solid lines) or –3°C (broken lines). C, GdnHCl denaturation of the reduced reference (•) and cross-linked LGs () monitored by ellipticity at 220 nm.

View larger version (17K): [in this window] [in a new window]   FIG. 10. -Chymotrypsin digestion of three LG species analyzed by SDS-PAGE. See "Experimental Procedures" for details. Reference, reduced reference LG; Non-covalent, non-covalent aggregates of LG; Cross-linked, cross-linked LG. Arrows 1 and 2 indicate the monomeric and cross-linked LGs, respectively. The samples containing -chymotrypsin were incubated at 25 °C for 0, 5, 30, and 180 min.

	DISCUSSION

TOP ABSTRACT INTRODUCTION EXPERIMENTAL PROCEDURES RESULTS DISCUSSION REFERENCES

View larger version (26K): [in this window] [in a new window]   FIG. 11. Schemes for competition between non-covalent aggregation and tTG-catalyzed cross-linking of a denaturing protein. A, two possible cascades of events occurring under competition. N, native state; D, denatured state. B, a scheme for LG. D1, a mildly denatured state containing tertiary structures; D2, a denatured state without tertiary structures; D3, a more extensively denatured state than D2.

Cross-linking did not affect the decay of []₂₉₃ (Fig. 8A) but inhibited the slower phase of the change in []₂₀₆ (Fig. 8B). This observation indicated that cross-linking blocked the transition from the D₂ state to D₃ and trapped the molecules as soluble multimers (Fig. 11B). The decay constant of the non-aggregated fraction by SEC for the cross-linked sample was 4.2 ± 0.2 h (Figs. 5C and 6), which was the same as that observed for the decay of the tertiary structure ( = 4.2 ± 0.3 h). This result indicated that the cross-linking reaction occurred rapidly in the D₂ state of LG. The rate-limiting step of the cross-linking reaction is probably the conformational change of LG. The extensive unfolding from D₂ to D₃ could also be reverted by the action of tTG (Fig. 7C). The decay time constant of the N fraction of the non-covalent aggregation processes (4.4 ± 0.4 h; Fig. 5B) was also identical to that of []₂₉₃ of the reduced reference LG, suggesting that the non-covalent aggregation was also initiated in the D₂ state (Fig. 11B).

Properties of Cross-linked LG Molecules—The cross-linked LG could not form precipitates under low ionic strength. Higher concentrations of CaCl₂ were required for its phase separation than for the reduced LG monomer (Fig. 3). This indicated that cross-linking weakened the intermolecular attractive forces or, alternatively, that it enhanced the electrostatic repulsion. The observation that the effect of tTG on the aggregation of LA was much weaker than that of LG and BSA (Fig. 1, A–C) can also be explained by variations in force balancing; the attractive force enhanced by unfolding of LA was probably too strong to be overcome by the cross-linking effect.

The change in the force balance caused by the tTG activity could have originated from the conformational shift of the unfolded LG by cross-linking because cross-linking substantially suppressed unfolding of the secondary structure (Fig. 8B). Furthermore, the residual structures with a hydrophobic core were more stable for the cross-linked LG than for the reduced reference (Fig. 9). It is plausible that cross-linking trapped LG in the conformation with less exposure of the hydrophobic core, which would reduce the hydrophobic attractive force among the molecules and increase the solubility of the unfolded proteins. Alternatively, cross-linking may also have altered the charge distribution on the unfolded molecules. All of the protein species used in the present study were acidic and carried net negative charges at pH 7.5. Formation of one isopeptide cross-link removes one positive charge on lysine from the proteins and increases their net negative charge. This could enhance the intermolecular electrostatic repulsion, which might explain the high solubility of the cross-linked molecules.

Biological Implications and Conclusion—Structurally unfolded protein molecules expose their hydrophobic interiors to the aqueous environment and therefore exhibit a strong tendency to form insoluble aggregates. This phenomenon has profound biological significance related to biosynthesis and biological disposal of proteins (30–34). The present study has suggested that the tTG-catalyzed cross-linking reaction did not always enhance protein aggregation but sometimes showed an inhibitory effect. This view is important, as tTG is believed to play key roles in apoptosis and human degenerative diseases (14, 22). In the case where cross-linking increases the solubility of the damaged proteins, these proteins might be removed more efficiently from the intra- and extracellular spaces by fluid flow or proteolysis. Cross-linking could also suppress the pathogenic amyloid-type aggregation. In fact, Lai et al. (21) showed that the cross-linking of polyglutamine-containing proteins increased their solubility and inhibited their fibril formation. Soluble oligomers of pathogenic proteins are not always benign and could be real pathogens for degenerative disease (12).

However, it should also be emphasized that tTG-catalyzed cross-linking does not necessarily inhibit protein aggregation and precipitation. We found that the effect of tTG on the aggregation process was strongly dependent on the species of the substrate proteins (Fig. 1, A–C). Furthermore, when cross-linking occurs with the substrate proteins in an extremely high concentration, it will induce gelation of the proteins. This is probably the case for blood clotting and skin keratin formation. It should also be noted that tTG and N-(-L-glutamyl)-L-lysine linkage are often co-localized with the intracellular inclusions in patients with the neurodegenerative diseases (36–39). Cultured cell models over-expressing tTGase and/or amyloidogenic proteins, such as , -synuclein, and huntingtin, have also been shown to exhibit tTGase-induced intracellular cross-linking and deposit formation (35, 38, 39). These observations suggested that tTG-catalyzed cross-linking enhances the aggregation and deposition of some pathogenic proteins in vivo. It is possible that tTG-catalyzed cross-linking modifies protein aggregation and deposition in vivo in a variety of fashions, including both enhancement and inhibition of aggregation depending on the target protein species and solution conditions. Further studies will be required to examine larger numbers of protein species under a variety of solution conditions, to establish the biological significance of the present findings.

	FOOTNOTES

 
^* This work was supported by Grant-in-aid for Scientific Research 15659050 from the Ministry of Education, Science, Sports, and Culture, Japan and by Core Research for Evolutional Science and Technology (CREST) of Japan Science and Technology Corporation. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

To whom correspondence should be addressed. Tel.: 81-776-61-8307; Fax: 81-776-61-8101; E-Mail: konno{at}fmsrsa.fukui-med.ac.jp.

¹ The abbreviations used are: TG, transglutaminase; tTG, a tissue-type transglutaminase; LG, bovine -lactoglobulin A; LA, human -lactalbumin; BSA, bovine serum albumin; DTT, dithiothreitol; SEC, size-exclusion gel chromatography.

	REFERENCES

TOP ABSTRACT INTRODUCTION EXPERIMENTAL PROCEDURES RESULTS DISCUSSION REFERENCES

 

1. Minton, A. P. (2001) J. Biol. Chem. 276, 10577–10580[Free Full Text]
2. Ellis, R. J. (2001) Curr. Opin. Struct. Biol. 11, 114–119[CrossRef][Medline] [Order article via Infotrieve]
3. Pedersen, J. S., Hansen, S., and Bauer, R. (1994) Eur. Biophys. J. 22, 379–389[Medline] [Order article via Infotrieve]
4. Muschol, M., and Rosenberger, F. (1997) J. Chem. Phys. 107, 1953–1962[CrossRef]
5. Piazza, R. (2000) Curr. Opin. Colloid Interface Sci. 5, 38–43
6. Kulkarni, A. M., Dixit, N. M., and Zukoski, C. F. (2003) Faraday Discuss. 123, 37–50[CrossRef][Medline] [Order article via Infotrieve]
7. Stradner, A., Sedgwick, H., Cardinaux, F., Poon, W. C., Egelhaaf, S. U., and Schurtenberger, P. (2004) Nature 432, 492–495[CrossRef][Medline] [Order article via Infotrieve]
8. Kelly, J. W. (1998) Curr. Opin. Struct. Biol. 8, 101–106[CrossRef][Medline] [Order article via Infotrieve]
9. Prusiner, S. B., Scott, M. R., DeArmond, S. J., and Cohen, F. E. (1998) Cell 93, 337–348[CrossRef][Medline] [Order article via Infotrieve]
10. Selkoe, D. J., and Schenk, D. (2003) Annu. Rev. Pharmacol. Toxicol. 43, 545–584[CrossRef][Medline] [Order article via Infotrieve]
11. Dobson, C. M. (2003) Nature 426, 884–890[CrossRef][Medline] [Order article via Infotrieve]
12. Caughey, B., and Lansbury, P. T. (2003) Annu. Rev. Neurosci. 26, 267–298[Medline] [Order article via Infotrieve]
13. Greenberg, C. S., Birckbichler, P. J., and Rice, R. H. (1991) FASEB J. 5, 3071–3077[Abstract]
14. Fesus, L., and Piacentini, M. (2002) Trends Biochem. Sci. 27, 534–539[CrossRef][Medline] [Order article via Infotrieve]
15. Lorand, L., and Graham, R. M. (2003) Nat. Rev. Mol. Cell. Biol. 4, 140–156[CrossRef][Medline] [Order article via Infotrieve]
16. Lorand, L. (1996) Proc. Natl. Acad. Sci. U. S. A. 93, 14310–14313[Free Full Text]
17. Lesort, M., Tucholski, J., Miller, M. L., and Johnson, G. V. (2000) Prog. Neurobiol. 61, 439–463[CrossRef][Medline] [Order article via Infotrieve]
18. Selkoe, D. J. (2002) Neurochem. Int. 40, 13–16[CrossRef][Medline] [Order article via Infotrieve]
19. Kim, S. Y., Jeitner, T. M., and Steinert, P. M. (2002) Neurochem. Int. 40, 85–103[CrossRef][Medline] [Order article via Infotrieve]
20. Konno, T., Morii, T., Hirata, A., Sato, S., Oiki, S., and Ikura, K. (2005) Biochemistry 44, 2072–2079[CrossRef][Medline] [Order article via Infotrieve]
21. Lai, T. S., Tucker, T., Burke, J. R., Strittmatter, W. J., and Greenberg, C. S. (2004) J. Neurochem. 88, 1253–1260[CrossRef][Medline] [Order article via Infotrieve]
22. Chen, J. S., and Mehta, K. (1999) Int. J. Biochem. Cell Biol. 31, 817–836[CrossRef][Medline] [Order article via Infotrieve]
23. Ikura, K., Sakurai, H., Okuma, K., Sasaki, R., and Chiba, H. (1985) Agric. Biol. Chem. 49, 3527–3531
24. Laemmli, U. K. (1970) Nature 227, 680–685[CrossRef][Medline] [Order article via Infotrieve]
25. Goldstein, D. A. (1979) Biophys. J. 26, 235–242[Medline] [Order article via Infotrieve]
26. Aboumahmoud, R., and Savello, P. (1990) J. Dairy Sci. 73, 256–263[Abstract]
27. Matsumura, Y., Chanyongvorakul, Y., Kumazawa, Y., Ohtsuka, T., and Mori, T. (1996) Biochim. Biophys. Acta 1292, 69–76[CrossRef][Medline] [Order article via Infotrieve]
28. Privalov, P. L., and Gill, S. J. (1988) Adv. Protein Chem. 39, 191–234[Medline] [Order article via Infotrieve]
29. Privalov, P. L. (1990) Crit. Rev. Biochem. Mol. Biol. 25, 281–305[Medline] [Order article via Infotrieve]
30. Hartl, F. U., and Martin, J. (1995) Curr. Opin. Struct. Biol. 5, 92–102[CrossRef][Medline] [Order article via Infotrieve]
31. Ellis, R. J. (1999) Curr. Biol. 9, R137–R139[CrossRef][Medline] [Order article via Infotrieve]
32. Sakahira, H., Breuer, P., Hayer-Hartl, M. K., and Hartl, F. U. (2002) Proc. Natl. Acad. Sci. U. S. A. 99, Suppl. 4, 16412–16418[Abstract/Free Full Text]
33. Berke, S. J., and Paulson, H. L. (2003) Curr. Opin. Genet. Dev. 13, 253–261[CrossRef][Medline] [Order article via Infotrieve]
34. Roos-Mattjus, P., and Sistonen, L. (2004) Ann. Med. 36, 285–295[CrossRef][Medline] [Order article via Infotrieve]
35. Karpuj, M. V., Garren, H., Slunt, H., Price, D. L., Gusella, J., Becher, M. W., and Steinman, L. (1999) Proc. Natl. Acad. Sci. U. S. A. 96, 7388–7393[Abstract/Free Full Text]
36. Zemaitaitis, M. O., Lee, J. M., Troncoso, J. C., and Muma, N. A. (2000) J. Neuropathol. Exp. Neurol. 59, 983–989[Medline] [Order article via Infotrieve]
37. Citron, B. A., Suo, Z., SantaCruz, K., Davies, P. J., Qin, F., and Festoff, B. W. (2002) Neurochem. Int. 40, 69–78[CrossRef][Medline] [Order article via Infotrieve]
38. Zainelli, G. M., Ross, C. A., Troncoso, J. C., and Muma, N. A. (2003) J. Neuropathol. Exp. Neurol. 62, 14–24[Medline] [Order article via Infotrieve]
39. Junn, E., Ronchetti, R. D., Quezado, M. M., Kim, S. Y., and Mouradian, M. M. (2003) Proc. Natl. Acad. Sci. U. S. A. 100, 2047–2052[Abstract/Free Full Text]

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