Clathrin and heterotetrameric adaptor protein coats in Drosophila melanogaster

Clathrin-coated vesicles carry cargo from the plasma membrane and the trans-Golgi network into the endosomal system. Clathrin heavy and light chains assemble into three-legged triskelia that polymerize into a lattice over the budding membrane. Heterotetrameric adaptor protein (AP) complexes, each made of two large subunits, a medium (mu) and a small (sigma) subunit, select cargo and link the membrane to the coat. AP-2 acts in endocytosis at the plasma membrane, including synaptic vesicle recycling; AP-1 acts at the trans-Golgi network and endosomes. AP-3 sorts cargo from endosomes towards lysosome-related organelles; in Drosophila the AP-3 subunits are encoded by the classic eye-colour genes garnet (g), ruby (rb), carmine (cm) and orange (or), whose mutants are defective in pigment granule biogenesis.

Boundary. The module contains clathrin and the three heterotetrameric adaptor complexes that FlyBase groups. AP-1 and AP-2 share a single beta subunit in Drosophila (AP-1-2beta), so that gene appears in both adaptor variants. AP-3 can also act independently of clathrin; it is kept here because FlyBase groups it with the other adaptor complexes. Monomeric adaptors, dynamin and uncoating factors are outside the module. The adaptor complexes carry their activity at complex level: clathrin-cargo adaptor activity (GO:0035615) for AP-1 and AP-2, whose subunits carry it in GOA (IBA, IMP, IC), and the general cargo adaptor activity (GO:0140312) for AP-3, which can act without clathrin and whose subunits carry cargo adaptor terms by ISS and IBA. Clathrin itself is a structural coat component and has no annoton function. FlyBase groups realized by this module: CLATH (FBgg0000123), AP (FBgg0000151). Subgroups folded into it: AP3, AP1, AP2. Participants were generated from the FlyBase gene-group membership and mapped to UniProtKB by projects/FLYBASE_GENE_GROUPS/generate_modules.py from module_specs/dmel_clathrin_adaptor_coats.yaml. None of the member genes has a gene review in this repository yet.