pfam14603: hSH3 (This model is not part of the current CDD release)
Helically-extended SH3 domain
This domain is the 70 C-terminal residues of ADAP - Adhesion and de-granulation promoting adapter protein. It shows homology to SH3 domains; however, conserved residues of the fold are absent. It thus represents an altered SH3 domain fold. An N-terminal, amphipathic, helix makes extensive contacts to residues of the regular SH3 domain fold thereby creating a composite surface with unusual surface properties. The domain can no longer bind conventional proline-rich peptides. There are key phosphorylation sites within the two hSH3 domains and it would appear that binding at these sites does not materially affect the folding of these regions although the equilibrium towards the unfolded state may be slightly altered. The binding partners of the hSH3 domains are still unknown.
Jiyao W et al.(2023). "The conserved domain database in 2023.",