Enables several functions, including Rab geranylgeranyltransferase activity; small GTPase binding activity; and zinc ion binding activity. Involved in protein geranylgeranylation. Part of Rab-protein geranylgeranyltransferase complex. Orthologous to human RABGGTB (Rab geranylgeranyltransferase subunit beta). [provided by Alliance of Genome Resources, Apr 2022]