9.B.278.1.1
The Adaptor Protein Complex, AP1 with subunits β1 (AP1B1, 949 aas), γ1 (AP1G1, 822 aas), μ1 (AP1M1; 423 aas) and σ1 (AP1S1, 158 aas).  Subunits of clathrin-associated adaptor protein complex 1 form a complex that plays a role in protein sorting in the late-Golgi/trans-Golgi network (TGN) and/or endosomes. The AP complexes mediate both the recruitment of clathrin to membranes and the recognition of sorting signals within the cytosolic tails of transmembrane cargo molecules (Guardia et al. 2018). These complexes therefore play a role in protein insertion into organellar membranes.  There is one isoform of β1, two of γ1, two of
μ1, and three of σ1. Only one iso-form of each is included here.  Although there are 5 such complexes in humans (AP-1 - 5), and many eukaryotic organisms have one of more of them, only AP1 of humans is tabulated in TCDB (Guardia et al. 2018). Parts of subunits β1 and γ1 are homologous, and parts of subunits μ1 and σ1 show significant sequence similarity, suggestiong homology. Subunits β and γ are homologous as are subunits sigma and mu.  The KIDAR syndrome is associated with a AP1B1 variant (Kaniganti et al. 2025).