Possible Interaction: Leucine and Tyrosine

“Elevated branched-chain amino acids (BCAA; leucine , isoleucine, and valine) in MSUD can deplete brain tyrosine and tryptophan (the precursors of monoamine neurotransmitters, dopamine (DA) and serotonin (5-hydroxytryptamine; 5-HT)) through competition via the large neutral amino acid transporter.”

“Both of the tyrosines and the leucine or isoleucine residues that follow them were critical.”

“In addition, a component of Na(+)-independent tryptophan, tyrosine and phenylalanine transport in 1-cell and 2-cell conceptuses and in blastocysts resisted inhibition by L-leucine.”

“Brain concentrations of tyrosine , phenylalanine and tryptophan were significantly reduced in animals receiving supplements of leucine for two and six weeks.”

“sites, it is uncertain how this regulation occurs, although phosphorylation of tyrosine in the carboxyl terminus of VEGFR-2 and leucine motif-mediated helix-helix interactions may play important roles [8].”

“Amino acids, such as valine, isoleucine and leucine compete with tyrosine and tryptophan for transport into the brain and might thus affect the central serotonin and catecholamine patterns.”

“Plasma concentrations of essential amino acids, including threonine, methionine, isoleucine, valine, tyrosine , and phenylalanine were significantly decreased by leucine infusion.”

“During the infusion of leucine its concentration rose four- to six-folds, while the concentrations of several other amino acids declined continually, the effect being most pronounced for isoleucine (-55% of initial value), methionine (-55%), valine (-40%), tyrosine (-35%) and phenylalanine (-35%).”

“These results suggest that leucine regulates the plasma concentrations of branched-chain amino acids, methionine, phenylalanine, and tyrosine , and that system L amino acid transporters are involved in the leucine action.”

“Interestingly, tyrosine phosphorylation levels of cardiac Na(+) channels (I(Na)) and L-type Ca(2+) channels (I(Ca, L )) were significantly increased at time points corresponding to the alteration of EGFR phosphorylation levels during reperfusion.”