The Mouse t-Complex-encoded Protein Tctex-1 Is a Light Chain of Brain Cytoplasmic Dynein*
- Stephen M. King¶∥,
- James F. Dillman III″,
- Sharon E. Benashski¶,
- R. John Lye″,
- Ramila S. Patel-King¶ and
- K. Kevin Pfister″
- From the ¶ Department of Biochemistry, University of Connecticut Health Center, Farmington, Connecticut 06032-3305 and the
- ″ Department of Cell Biology, University of Virginia Health Science Center, Charlottesville, Virginia 22908-0439
- ∥ To whom correspondence should be addressed: Dept. of Biochemistry, University of Connecticut Health Center, 263 Farmington Ave, Farmington, CT 06032-3305. Tel.: 860-679-3347; Fax: 860-679-3408; E-mail: king{at}panda.uchc.edu
Abstract
Mammalian brain cytoplasmic dynein contains three light chains of Mr = 8,000, 14,000, and 22,000 (King, S. M., Barbarese, E., Dillman, J. F., III, Patel-King, R. S., Carson, J. H., and Pfister, K. K. (1996) J. Biol. Chem. 271, 19358-19366). Peptide sequence data (16/16 residues correct) implicate the Mr = 14,000 polypeptide as Tctex-1, a protein encoded within the mouse t-complex. Tctex-1 cosediments with microtubules and is eluted with ATP or salt but not with GTP as expected for a dynein subunit. The ATP-eluted protein precisely cosediments with known cytoplasmic dynein proteins in sucrose density gradients. Tctex-1 also is immunoprecipitated from brain and other tissue homogenates by a monoclonal antibody raised against the 74-kDa cytoplasmic dynein intermediate chain. Quantitative densitometry indicates that Tctex-1 is a stoichiometric component of the dynein complex. As Tctex-1 is a candidate for involvement in the transmission ratio distortion (meiotic drive) of mouse t-haplotypes, these results suggest that cytoplasmic dynein dysfunction may play an important role in non-mendelian chromosome segregation.
Footnotes
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↵* This study was supported by a New Investigator award from the Patrick and Catherine Weldon Donaghue Medical Research Foundation (to S. M. K.) and by Grants GM 51293 (to S. M. K.) and NS 29996 (to K. K. P.) from the National Institutes of Health. The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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↵1 The abbreviations used are:
- DHC
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dynein heavy chain
- IC
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intermediate chain
- LIC
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light intermediate chain
- LC
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light chain.
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↵2 Although described as a peripheral sperm membrane protein (Huw et al., 1995), we have recently found that a Chlamydomonas homologue of Tctex-2 (sharing 35% identity and 56% similarity; P(n) = 1.8 × 10−21) is a LC of flagellar outer arm dynein (61).
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↵3 Message for the candidate rp3 protein is found at high levels in brain, retina, lymphoblasts and fibroblasts but is present only in relatively small amounts in lung, liver, spleen, heart, muscle, esophagus, and testis (43).
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- Received July 30, 1996.
- Revision received September 18, 1996.
- © 1996 by The American Society for Biochemistry and Molecular Biology, Inc.
