An SH3 domain is a protein module, a characteristic peptide sequence. It is used in signal transduction proteins, often in pathways involving tyrosine kinases. SH3 domains bind to proline-rich sequences (or polyproline helices). SH stands for src homology.
with 1 and 4 being aliphaticamino 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.
SH3domains are modules of ~60 residues that bind to proline-rich peptides in a sequence-specific manner.
Interestingly, its placement on the surface of the SH3domain appears very superficial with the prolines interacting with the aromatic residues on the hydrophobic face of the SH3domain.
This superficial contact is in contrast to the deeper binding groove used in the binding of the phospho-tyrosyl peptide on the surface of the SH2 domain.
Ribbon diagram of the SH3domain, α-spectrin, from chicken (Gallus gallus) (PDB accession code 1SHG), colored from blue (N-terminus) to red (C-terminus).
The SH3domain is found in proteins that interact with other proteins and they mediate assembly of specific protein complexes via binding to proline-rich peptides in their respective binding partner.
SH3domains are often found in functions concerning the cytoskeleton, the ras protein, and the src kinase.
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