ADP-ribosylation factor-binding protein GGA1

GGA1 (ADP-ribosylation factor-binding protein GGA1) is a 639-amino acid cytosolic adaptor protein that mediates protein sorting and trafficking between the trans-Golgi network (TGN) and endosomes. It recruits clathrin to the TGN in an ARF-dependent manner, binds ubiquitinated cargo molecules, and regulates retrograde transport of proteins including the phosphorylated form of BACE1 from endosomes back to the TGN (UniProt: Q9UJY5).

GGA1 functions in multiple trafficking pathways critical for cellular homeostasis, including export of the α2B-adrenergic receptor to the cell surface and targeting of the PKD1:PKD2 complex to ciliary membranes. Its role in BACE1 retrograde transport positions it within proteolytic pathways relevant to amyloid precursor protein metabolism.

GGA1 shows increased abundance in Alzheimer's disease brain tissue. In post-mortem AD brain samples compared to age-matched controls, GGA1 was upregulated with a mean log2 fold-change of 0.60 across analyzed subcellular fractions (Chaparral AD proteomics). This elevation may reflect altered protein trafficking and accumulation processes characteristic of AD neuropathology.