Component of the BLOC-1 complex, a complex that is required for normal biogenesis of lysosome-related organelles (LRO), such as platelet dense granules and melanosomes. In concert with the AP-3 complex, the BLOC-1 complex is required to target membrane protein cargos into vesicles assembled at cell bodies for delivery into neurites and nerve terminals. The BLOC-1 complex, in association with SNARE proteins, is also proposed to be involved in neurite extension. May play a role in intracellular vesicle trafficking, particularly in the vesicle-docking and fusion process (By similarity). Homodimer. Octamer composed of one copy each BLOC1S1, BLOC1S2, BLOC1S3, BLOC1S4, BLOC1S5, BLOC1S6, DTNBP1/BLOC1S7 and SNAPIN/BLOC1S8. The BLOC-1 complex associates with the AP-3 protein complex and membrane protein cargos. Interacts with BLOC1S4, BLOC1S5, DTNBP1/BLOC1S7, F-actin, SNAP25 isoform 1 and isoform 2, SNAP47 and STX12 (By similarity). Component of the biogenesis of lysosome-related organelles complex 1 (BLOC-1) composed of BLOC1S1, BLOC1S2, BLOC1S3, BLOC1S4, BLOC1S5, BLOC1S6, DTNBP1/BLOC1S7 and SNAPIN/BLOC1S8. It can exist as a soluble protein as well as a peripheral membrane protein. Belongs to the BLOC1S6 family.