Src homology 3 domain of an unknown subfamily of proteins with similarity to Protein kinase C and Casein kinase Substrate in Neurons (PACSIN) proteins
PACSINs, also called Synaptic dynamin-associated proteins (Syndapins), act as regulators of cytoskeletal and membrane dynamics. They bind both dynamin and Wiskott-Aldrich syndrome protein (WASP), and may provide direct links between the actin cytoskeletal machinery through WASP and dynamin-dependent endocytosis. Vetebrates harbor three isoforms with distinct expression patterns and specific functions. PACSINs contain an N-terminal F-BAR domain and a C-terminal SH3 domain. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.