it appears that at least two separate neutral amino acid transport systems are operative at the blood-tissue interface of the salivary epithelium : ( i ) a na+-dependent alanine-serine-cysteine preferring type of carrier exhibiting a high affinity for amino acids with short , polar or linear side chains and ( ii ) a na+-independent leucine preferring type of carrier selective for large neutral amino acids .
C0036720
serine
C0301715
neutral