Enables small GTPase binding activity. Involved in several processes, including positive regulation of ERK1 and ERK2 cascade; positive regulation of bone resorption; and positive regulation of cell differentiation. Predicted to be located in endoplasmic reticulum and membrane. Predicted to be integral component of membrane. Predicted to be part of plasma membrane proton-transporting V-type ATPase complex. Is expressed in integumental system; nervous system; sensory organ; and tail. Human ortholog(s) of this gene implicated in immunodeficiency 47. Orthologous to human ATP6AP1 (ATPase H+ transporting accessory protein 1). [provided by Alliance of Genome Resources, Apr 2022]