CLONING AND SEQUENCING OF A GENE CODING FOR AN ACTIN-BINDING PROTEIN OF SACCHAROMYCES-EXIGUUS

The actin binding protein Abp1p of the yeast Saccharomyces cerevisiae is thought to be involved in the spatial organisation of cell surface growth. It contains a potential actin binding domain and an SH-3 regio n, a common motif of many signal transduction proteins [1]. We have cl oned and sequenced an ABP1 homologous gene of Saccharomyces exiguus, a yeast which is only distantly related to S. cerevisiae. The protein e ncoded by this gene is slightly larger than the respective S. cerevisi ae protein (617 versus 592 amino acids). The two genes are 67.4% ident ical and the deduced amino acid sequences share an overall identity of 59.8%. The most conserved regions are the 148 N-terminal amino acids containing the potential actin binding site and the 58 C-terminal amin o acids including the SH3 domain. In addition, both proteins contain a repeated motif of unknown function which is rich in glutamic acids wi th the sequence EEEEEEEAPAPSLPSR in the S. exiguus Abp1p.