AP-1 complex subunit gamma-1

AP-1 complex subunit gamma-1 (AP1G1) is a subunit of the clathrin-associated adaptor protein complex 1, which mediates protein sorting and clathrin recruitment to membranes (UniProt: O43747). The protein recognizes cargo sorting signals and plays a key role in trafficking between the trans-Golgi network and endosomes, including the trafficking of transferrin, furin, and cathepsin D.

AP1G1 is expressed in neural tissues and mutations in AP1G1 cause Usmani-Riazuddin syndrome, both autosomal dominant and recessive forms (UniProt: O43747). These neurodevelopmental disorders present with global developmental delay, intellectual disability, speech delay, hypotonia, and behavioral abnormalities, with variable seizures and limb anomalies.

In Alzheimer's disease, AP1G1 shows ambiguous regulation across subcellular fractions of post-mortem AD brain tissue (Chaparral AD proteomics), with a mean log2 fold-change of −0.30 relative to age-matched controls. This subtle, fraction-dependent pattern suggests context-dependent changes in protein trafficking machinery in AD pathology.