Enables signaling receptor regulator activity and type 4 melanocortin receptor binding activity. Involved in energy homeostasis; energy reserve metabolic process; and feeding behavior. Predicted to be located in membrane. Predicted to be integral component of membrane. Predicted to be active in endoplasmic reticulum and plasma membrane. Human ortholog(s) of this gene implicated in obesity. Orthologous to human MRAP2 (melanocortin 2 receptor accessory protein 2). [provided by Alliance of Genome Resources, Apr 2022]