This gene encodes a type 1 transmembrane protein that is important for trafficking amino acid transporters to the apical brush border of proximal tubules. The encoded protein binds to amino acid transporters and regulates their expression on the plasma membrane. It also plays a role in controlling insulin exocytosis by regulating formation of the SNARE (soluble N-ethylmaleimide-sensitive-factor attachment protein receptor) complex in pancreatic beta cells. The extracellular domain of the encoded protein may be cleaved and shed from the plasma membrane specifically in pancreatic beta cells.