Inhibition by L-phenylalanine of tryptophan transport by synaptosomal plasma membrane vesicles: implications in the pathogenesis of phenylketonuria.
Phenylalanine is accumulated in the genetically linked deficiency phenylketonuria. The effect of L-phenylalanine on the transport of tryptophan was studied using membrane vesicles from rat-brain synaptosomes. Phenylalanine at similar concentrations to those found in phenylketonuric patients competitively inhibits tryptophan uptake, with a Ki of the same order as the Km for tryptophan. This inhibition could be responsible for the depletion of serotonin found in phenylketonuria.
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D001693:Biological Transport, Active / Q000187:drug effects; D001921:Brain / Q000648:ultrastructure; D006801:Humans; D007700:Kinetics; D008297:Male; D010649:Phenylalanine / Q000494:pharmacology*; D010661:Phenylketonurias / Q000209:etiology*; D051381:Rats; D011919:Rats, Inbred Strains; D013570:Synaptic Membranes / Q000378:metabolism; D013574:Synaptosomes / Q000378:metabolism*; D014364:Tryptophan / Q000378:metabolism*
D010649:Phenylalanine; D014364:Tryptophan