SAM AS A PROTEIN-INTERACTION DOMAIN INVOLVED IN DEVELOPMENTAL REGULATION

More than 60 previously undetected SAM domain-containing proteins have been identified using profile searching methods. Among these are over 40 EPH-related receptor tyrosine kinases (RPTK), Drosophila bicaudal- C, a p53 from Loligo forbesi, and diacylglycerol-kinase isoform delta. This extended dataset suggests that SAM is an evolutionary conserved protein binding domain that is involved in the regulation of numerous developmental processes among diverse eukaryotes. A conserved tyrosine in the SAM sequences of the EPH related RPTKs is likely to mediate ce ll-cell initiated signal transduction via the binding of SH2 containin g proteins to phosphotyrosine.