SH3 domain

An SH3 domain is a protein module, a characteristic peptide sequence. It is used in signal transduction proteins, often in pathways involving tyrosin kinases[?]. SH3 domains bind to proline-rich sequences (or polyproline helices). SH stands for src[?] homology.

SH3 domains have a consensus sequence[?]:

 -X-P-p-X-P-
  1 2 3 4 5

with 1 and 4 being aliphatic[?] amino acids, 2 and 5 always and 3 sometimes being proline. The sequence binds to the hydrophobic pocket of the SH3 domain.

SH3 domains are often found in functions concerning the cytoskeleton, the ras protein[?], and the src kinase[?]. They also increase the substrate specificity of tyrosine kinases by binding far away from the catalytic center[?] of the kinase.