Predicted to enable R-SMAD binding activity and WW domain binding activity. Predicted to be involved in negative regulation of SMAD protein complex assembly; negative regulation of pathway-restricted SMAD protein phosphorylation; and negative regulation of transforming growth factor beta receptor signaling pathway. Predicted to be located in endosome membrane. Predicted to be active in Golgi membrane and early endosome membrane. Orthologous to human PMEPA1 (prostate transmembrane protein, androgen induced 1). [provided by Alliance of Genome Resources, Apr 2022]