May regulate the synthesis and function of lysosomes and of highly specialized organelles, such as melanosomes and platelet dense granules. Regulates intracellular vesicular trafficking in fibroblasts. May be involved in the regulation of general functions of integrins. Component of the biogenesis of lysosome-related organelles complex-2 (or BLOC2) composed of HPS3, HPS5 and HPS6. Interacts with HPS6 and HPS3. May interact with all alpha-integrin chains that have an aromatic residue before the first lysine of the conserved KXGFFKR motif, including ITGA2, ITGA3, ITGA5 and ITGA6. Widely expressed, with lowest expression in skeletal muscle and spleen. Defects in Hps5 are the cause of Hermansky-Pudlak-like syndrome, a syndrome characterized by hypopigmented eyes and coat, melanosomes greatly reduced in number and morphologically bizarre, kidney proximal tubules secreting lysosomal enzymes into urine at greatly reduced rates, platelet dense granules deficient in critical components, such as serotonin and adenine nucleotides, leading to functionally abnormal platelets and prolonged bleeding times, and mast cell granules undergoing unregulated 'kiss-and-run' fusion at the plasma membrane. Belongs to the HPS5 family.