the livr locus , which leads to a trans-recessive derepression of branched-chain amino acid transport and periplasmic branched-chain amino acid-binding proteins , is responsible for greatly increased sensitivity toward growth inhibition by leucine , valine , and serine and , as shown previously , for increased sensitivity toward toxicity by branched-chain amino acid analogues , such as 4-azaleucine or 5',5',5'-trifluoroleucine .
C0042285
valine
C0002521
branched-chain amino acid