Claim: Stp4 transcribes for an integral membrane protein that is situated in the plasma membrane of sink tissues and is classed as a symporter, an integral membrane protein that is involved in the transport of many differing types of molecules across the cell membrane.
Evidence: The gene transcribes for an integral membrane protein that is situated in the plasma membrane of sink tissues such as roots, anthers and vascular tissue. The protein is classed as a symporter since sodium ions are also transported concurrently in the same direction. A symporter is an integral membrane protein that is involved in the transport of many differing types of molecules across the cell membrane.