**2.1 STRA6 (stimulated by retinoic acid 6)**

STRA6 is a cell surface protein that functions as a receptor to accept all-trans retinol from the extracellular retinol-binding protein RBP4 and to transport retinol across the cell membrane. STRA6 removes the retinol from RBP4 and transfers it to RBP1 in the cytoplasm. STRA6 does not transport RA.
