Biogenesis of lysosomal organelles complex 3 subunit 1 (HPS1)

Biogenesis of lysosomal organelles complex 3 subunit 1 (HPS1) is a protein encoded by the *HPS1* gene that forms a core component of the BLOC-3 complex, together with HPS4. BLOC-3 is crucial for the formation, maturation, and trafficking of lysosome-related organelles (LROs), including melanosomes (involved in pigmentation) and platelet dense granules (important for blood clotting). HPS1 acts as part of a guanine nucleotide exchange factor (GEF) complex that activates Rab32 and Rab38 small GTPases, orchestrating the delivery and recycling of vesicular components necessary for specialized organelle function. Mutations in *HPS1* are the most common cause of Hermansky-Pudlak syndrome, an autosomal recessive disorder manifesting with albinism, bleeding tendency, and variable chronic organ involvement such as pulmonary fibrosis and inflammatory bowel disease. BLOC-3 assembly and its interaction with Rab GTPases are essential for proper pigmentation, immune responses, and secretory vesicle maturation. There are no known drugs that directly target HPS1; its variants serve as disease biomarkers for genetics-based diagnosis.

Other names

BLOC-3 complex member HPS1HPS1HPSBLOC3S1Hermansky-Pudlak syndrome 1 protein

Not applicable; HPS1 itself is not targeted by drugs, but disruption/mutation leads to disease