Adaptor Related Protein Complex 1 Associated Regulatory Protein (AP1AR)

GBAR, encodes a 302-amino acid protein containing a coiled-coil region and is predicted to be a peripheral membrane protein. C4ORF16 shares 89% identity at the protein level with the mouse homolog. Immunofluorescence and electron microscopy showed that C4ORF16 and AP1G1 colocalize in a juxtanuclear region and that C4ORF16 localizes primarily to late endocytic structures, but can also be found in trans-Golgi network (TGN), early endosomes, and the plasma membrane.Although C4ORF16 contains 3 potential binding motifs for the AP1G1 ear domain, coimmunoprecipitation with a C4ORF16 variant that lacks the coiled-coil domain demonstrated that, in vivo, the coiled-coil domain is required for AP1G1 binding. Downregulation of C4ORF16 with siRNA reduced the level of steady-state AP1G1 on membranes.