This gene encodes a component of BLOC-1 (biogenesis of lysosome-related organelles complex 1). Components of this complex are involved in the biogenesis of organelles such as melanosomes and platelet-dense granules. A mouse model for Hermansky-Pudlak Syndrome is mutated in the murine version of this gene. Alternative splicing results in multiple transcript variants. Read-through transcription exists between this gene and the upstream EEF1E1 (eukaryotic translation elongation factor 1 epsilon 1) gene, as well as with the downstream TXNDC5 (thioredoxin domain containing 5) gene.