ARL8 effector that promotes the coupling of endolysosomes to dynein-dynactin for retrograde transport along microtubules. Acts by binding both GTP-bound ARL8 and dynein-dynactin. In nonneuronal cells, promotes concentration of endolysosomes in the juxtanuclear area. In hippocampal neurons, drives retrograde transport of endolysosomes from the axon to the soma (PubMed:35314674). Positive regulator of macroautophagy in dendritic cells. Increases autophagic flux, probably by stimulating both autophagosome formation and facilitating tethering with lysosomes. Binds to phosphatidylinositol 3-phosphate (PtdIns3P) through its FYVE-type zinc finger (PubMed:26416964). Positive regulator of osteoclast bone-resorbing activity, possibly by promoting late endosome-lysosome fusion by acting as an adapter protein between RAB7A on late endosomes and LAMP2 on primary lysosomes (By similarity). {ECO:0000250|UniProtKB:Q3TYX8, ECO:0000269|PubMed:26416964, ECO:0000269|PubMed:35314674}. This is the function of ENSG00000188282 (RUFY4, RUN and FYVE domain containing 4).