SH3 — an abundant protein domain in search of a function

Abstract
Src‐homology 3 is a small protein domain of about 60 amino acid residues. It is probably made of β‐sheets. SH3 is present in a large number of eukaryotic proteins which are involved in signal transduction, cell polarization and membrane—cytoskeleton interactions. Here we review its occurrence and discuss possible functions of this domain.