May regulate the synthesis and function of lysosomes and of highly specialized organelles, such as melanosomes and platelet dense granules (PubMed:17041891). Acts as cargo adapter for the dynein-dynactin motor complex to mediate the transport of lysosomes from the cell periphery to the perinuclear region. Facilitates retrograde lysosomal trafficking by linking the motor complex to lysosomes, and perinuclear positioning of lysosomes is crucial for the delivery of endocytic cargos to lysosomes, for lysosome maturation and functioning (PubMed:25189619). Component of the biogenesis of lysosome-related organelles complex-2 (or BLOC2) composed of HPS3, HPS5 and HPS6. Interacts with HPS5 and HPS3 (PubMed:15030569, PubMed:25189619). Interacts with biogenesis of lysosome-related organelles complex-1 (BLOC1). Interacts with AP-3 complex (PubMed:16837549). Interacts with MNAT1 (Probable). Interacts with DCTN1 and dynein intermediate chain (PubMed:25189619). Ubiquitous. The disease is caused by variants affecting the gene represented in this entry.