• Hermansky–Pudlak syndrome;
  • Protein trafficking;
  • Vesicle fusion;
  • Platelet dense granule

This review focuses on the product of the pallidin (Pldn) gene, one of a number of genes that in mice are associated with pigmentation defects and platelet dense granule deficiency. A similar combination of defects is also observed in patients suffering from Hermansky–Pudlak (HPS) and Chediak–Higashi (CHS) syndromes. Pldn encodes a novel, ∼20-kDa protein that is expressed ubiquitously in mammalian tissues. The pallidin protein was found to bind to syntaxin 13, a member of the syntaxin family of soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs). As SNARE proteins mediate fusion of intracellular membranes, pallidin may play a role in membrane fusion events required for melanosome biogenesis.