We have determined the complete sequence of human vinculin, a cytoskeletal protein associated with cell-cell and cell-matrx junctions. Comparison of human and chicken embryo vinculin sequences shows that both proteins contain 1066 amino acids and exhibit a high level of sequence identity (>95%). The region of greatest divergence falls within three 112-amino acid repeats spanning residues 259-589. Interestingly, nematode vinculin lacks one of these central repeats. The regions of human vinculin that are N-and Cterminal to the repeats show 54% and 61% sequence identity, respectively, to nematode vinculin. Southern blots of human genomic DNA hybridized with short vinculin cDNA fragments indicate that there is a single vinculin gene. By using a panel of human-rodent somatic cell hybrids, the human vinculin gene was mapped to chromosome 10qll.2-qter.

We have analyzed the structure, origin and expression of the high-molecular-mass muscle-specific variant of vinculin, called meta-vinculin. The meta-vinculin-specific inserts from the human and avian molecules have been isolated and sequenced and the sequences confirmed via cloning of the corresponding cDNA. Comparison of the human, avian and determined porcine sequences revealed cross-species identity in the C-terminal half of the insert. Human and porcine meta-vinculin were highly similar in the insert region, showing only five amino acid exchanges; avian meta-vinculin showed 22 exchanges in the same region compared to human meta-vinculin and exhibited, in addition, one extra amino acid, making 69 in all. Each insert was flanked by characteristic KWSSK motifs.Evidence for two vinculin mRNA species in human uterus smooth muscle was provided by reverse transcription combined with the polymerase chain reaction, as well as by ribonuclease-mapping analysis of cDNA/mRNA hybrids. One of the mRNA species contained an additional 204-nucleotide insert that precisely encoded the meta-vinculin-specific peptide.Sequence analysis of the appropriate portion of the human vinculin gene showed that the section coding for the meta-vinculin-specific insert is present as a discrete exon. Thus, meta-vinculin and vinculin mRNA are generated by alternative splicing.Vinculin is a 11 7-kDa cytoskeletal protein associated with membrane actin-filament-attachment sites of cell-cell and cellmatrix adherens-type junctions [I, 21. Several studies have shown a remarkable microheterogeneity of vinculin in the form of antigenically indistinguishable isoelectrophoretic variants, some of which show tissue-specific expression [3-51. In addition to iso-vinculins, smooth muscle and striated muscle contain an 150-kDa protein, denoted as meta-vinculin, which shares similar peptide-map patterns, antigenic and functional properties with vinculin [6-1 I]. Meta-vinculin and vinculin are localized in the same cellular adhesive structures, in microfilament-associated membrane-bound plaques of smooth muscle, in intercalated discs and costameres of cardiac muscle, and in focal contacts of cultivated smooth-muscle cells [ l l , 121. Recently it was established that meta-vinculin may serve as a specific marker of smooth muscle [lo, 13, 141; it was identified in all human, chicken and porcine smooth muscles but not in non-muscle tissues and cultured cells [lo, 13, 141. The expression of meta-vinculin in human aortic smooth- To obtain a more complete understanding of the structural relationship between vinculin and meta-vinculin, the amino acid sequence of a porcine meta-vinculin-specific peptide was determined 1121. Porcine vinculin and meta-vinculin differ by a 68-residue insert, located close to the C-terminal part of the molecule [12]. The fact that no amino acid difference could be observed between vinculin and meta-vinculin apart from this peptide suggested that they are encoded by alternatively spliced transcripts derived from a single gene [12]. Furtherm...