Arf-GAP with SH3 domain, ANK repeat and PH domain-containing protein 1

ASAP1 (Arf-GAP with SH3 domain, ANK repeat and PH domain-containing protein 1) is a phosphatidylinositol 4,5-bisphosphate-dependent GTPase-activating protein that regulates ARF (ADP ribosylation factor) proteins, particularly ARF1, ARF5, and ARF6 (UniProt: Q9ULH1). The protein coordinates membrane trafficking and actin cytoskeleton remodeling through interactions with SRC and PIP2, and participates in ciliogenesis as part of a ciliary targeting complex containing Rab11, Rabin8, and ARF4.

ASAP1 is involved in cellular differentiation processes and vesicular trafficking pathways critical for proper intracellular transport and organellar function. While no primary disease associations are documented in UniProt, the protein's role in membrane dynamics and cytoskeletal regulation implicates it in processes relevant to neuronal homeostasis.

In Alzheimer's disease, ASAP1 is significantly downregulated in human post-mortem AD brain compared to age-matched controls (Chaparral AD proteomics), with a mean log2 fold-change of −1.191 across subcellular fractions in TMT-labeled quantitative proteomics. This reduction may reflect compromised membrane trafficking or cytoskeletal dysfunction associated with AD pathology.