[Mechanism of amino acid transport at the liver plasma membrane].

Several amino acid transport systems have been known in the liver: sodium-dependent systems A, ASC and N for neutral amino acids, a sodium-dependent system for glycine (system Gly), sodium independent systems L1 and L2 for neutral amino acids, and sodium dependent systems for anionic amino acids. Recent studies with isolated sinusoidal and canalicular membrane vesicles have revealed that sodium dependent transport of an anionic amino acid, glutamate, and glycine occurs at the canalicular membrane, not at the sinusoidal membrane. Furthermore, solubilization and reconstitution of systems A and N has been reported and a 100 kD protein responsible for system N transport has been identified in the rat liver.