Predicted to enable GTP binding activity; GTPase activity; and proton-transporting ATPase activity, rotational mechanism. Predicted to be involved in proton transmembrane transport. Predicted to be part of proton-transporting V-type ATPase, V0 domain. Is an ortholog of C. elegans rab-39. In C. elegans, rab-39 is involved in positive regulation of response to oxidative stress.