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mu-homology domain (MHD) of F-BAR domain-containing Fer/Cip4 homology domain-only protein 2 (FCH domain only 2 or FCHo2) and similar proteins This family corresponds to the MHD found in the ubiquitously expressed mammalian membrane-sculpting FCHo2 and similar proteins. FCHo2 represents a key initial protein that ultimately controls cellular nutrient uptake, receptor regulation, and synaptic vesicle retrieval. It is required for plasma membrane clathrin-coated vesicle (CCV) budding and marks sites of CCV formation. It binds specifically to the plasma membrane and recruits the scaffold proteins eps15 and intersectin, which subsequently engages the adaptor complex AP2 and clathrin, leading to coated vesicle formation. FCHo2 contains an N-terminal EFC/F-BAR domain, a proline-rich domain (PRD) in the middle region, and a C-terminal MHD. The crescent-shaped EFC/F-BAR domain can form an antiparallel dimer structure that binds PtdIns(4,5)P2-enriched membranes and can polymerize into rings to generate membrane tubules. The MHD is structurally related to the cargo-binding mu2 subunit of adaptor complex 2 (AP-2) and is responsible for the binding of eps15 and intersectin.
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