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 kinase]?s. SH3 domains bind to proline?-rich sequences (or polyproline helices).

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.