Subunit of clathrin-associated adaptor protein complex 1 that plays a role in protein sorting in the trans-Golgi network (TGN) and endosomes. The AP complexes mediate the recruitment of clathrin to membranes and the recognition of sorting signals within the cytosolic tails of transmembrane cargo molecules.
Belongs to the adaptor complexes medium subunit family. Contains 1 MHD (mu homology) domain.
Phosphorylation of membrane-bound AP1M1/AP1M2 increases its affinity for sorting signals.
Golgi apparatus. Cytoplasmic vesicle > clathrin-coated vesicle membrane. Component of the coat surrounding the cytoplasmic face of coated vesicles located at the Golgi complex.