Hermansky Pudlak Syndrome Protein 4 (HPS4)

Hermansky-Pudlak syndrome is a disorder of organelle biogenesis in which oculocutaneous albinism, bleeding, and pulmonary fibrosis result from defects of melanosomes, platelet dense granules, and lysosomes. Mutations in this gene as well as several others can cause this syndrome.HPS4 appears to be important in organelle biogenesis and is similar to the mouse """light ear""" protein. Five transcript variants encoding different isoforms have been found for this gene. In addition, transcript variants utilizing alternative polyadenylation signals exist.In addition to their identical phenotypes, le and ep mutant mice have identical abnormalities of melanosomes, and in transfected melanoma cells, the HPS4 and HPS1 proteins partially colocalize in vesicles of the cell body.