EQUUS-CABALLUS GELSOLIN - CDNA SEQUENCE AND PROTEIN STRUCTURAL IMPLICATIONS

We have generated and characterized the cDNA from equine smooth muscle that Encodes gelsolin, an actin-modulating protein. Overlapping cDNA clones synthesized by the reverse transcriptaseoplymerase chain reacti on and clones isolated from a horse genomic library provided the compl ete primary structure for the intracellular isoform of gelsolin, while cDNA complemented with protein sequence data produced the full-length primary transcript of the gelsolin isoform found circulating in equin e plasma. The deduced amino acid sequences of the intracellular and se creted versions of equine gelsolin infer polypeptides of 731 and 755 r esidues with apparent molecular masses of 80.7 kDa and 83.2 kDa, respe ctively. Multiple sequence alignment analysis of equine, human, porcin e, and murine orthologs of gelsolin demonstrates prominent similaritie s among all of these proteins, with the horse and human molecules exhi biting the largest degree of likeness with respect to polypeptide leng th and overall sequence composition. Both horse and human plasma gelso lins are comprised of 755 amino acids with 94% of the residues identic al, while the degree of sequence identity in the shorter (731 residues ) cytoplasmic gelsolins is 95 %. Analysis of the sequences and structu res of the six related domains that comprise gelsolin emphasizes the s trong correlation that exists between primary structural conservation among mammalian gelsolins and maintenance of the three-dimensional dom ain fold characteristic of members of this protein family.