FAP52, a Novel, SH3 Domain-containing Focal Adhesion Protein*
- From the ‡Biocenter Oulu and the Department of Pathology, University of Oulu, FIN-90220 Oulu, Finland and the¶Department of Radiotherapy and Oncology, Helsinki University Hospital, FIN-00290 Helsinki, Finland
Abstract
Src-homology 3 (SH3) domain is a 60–70-amino acid motif present in a large variety of signal transduction and cytoskeletal proteins. We used reverse transcriptase-polymerase chain reaction with degenerate and specific primers and chicken brain mRNA to clone a cDNA that codes for a novel SH3 domain-containing protein. The sequence predicts a 448-amino acid polypeptide with a molecular mass of 51,971 daltons. In the amino terminus, it shows a very high propensity for α-helicity, suggesting coiled-coil and possibly a higher order oligomeric arrangement. In the carboxyl terminus, there is a unique SH3 sequence. In Northern blotting, a major 3.7-kilobase and a minor 7.2-kilobase transcript was detected in most chicken tissues. In immunofluorescence microscopy and immunoelectron microscopy on cultured chicken fibroblasts, the protein was localized to focal adhesions in which it showed a distinct codistribution with the focal adhesion proteins vinculin, talin, and paxillin. Phosphoamino acid analysis showed that in cultured chicken heart fibroblasts, the protein contains phosphoserine, but no phosphothreonine or phosphotyrosine, and that the phosphorylation is not dependent on fibronectin. We propose this protein the name FAP52, for Focal Adhesion Protein of52 kDa, and suggest that it forms part of the multimolecular complex constituting focal adhesion sites.
Footnotes
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↵* This work was supported by the Medical Research Council of Finland, the Sigrid Juselius Foundation, and the Finnish Cancer Research Fund.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.
The nucleotide sequence(s) reported in this paper has been submitted to the GenBank™/EMBL Data Bank with accession number(s) Z50798.
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↵§ To whom correspondence should be addressed: Biocenter Oulu and Dept. of Pathology, University of Oulu, Kajaanintie 52 D, FIN-90220 Oulu, Finland. Tel.: 358-8-5375950 or 358-8-3152183; Fax: 358-8-3152183 or 358-8-330687; E-mail: lehto{at}csc.fi.
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↵1 The abbreviations used are: FA(s), focal adhesion(s); CEHF, chicken embryo heart fibroblast; CNBr, cyanogen bromide; FCS, fetal calf serum; PCR, polymerase chain reaction; RT, reverse transcriptase; PAGE, polyacrylamide electrophoresis; SH2, Src-homology 2; SH3, Src-homology 3; Pipes, 1,4-piperazinediethanesulfonic acid; bp, base pair(s); PBS, phosphate-buffered saline; RACE, rapid amplification of cDNA ends; TBS, Tris-buffered saline.
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- Received November 6, 1996.
- Revision received May 12, 1997.
