Transport of the alpha-amino-mono-carboxylic acid L-alanine by the beta-alanine carrier of the rabbit ileum.
The proposal that the beta-alanine carrier of the rabbit ileum is a high affinity carrier of the neutral amino acids was examined by means of measurements of influx across the brush border membrane of the intact epithelium using L-alanine as a representative of the neutral amino acids. Confirming the proposal, evidence was provided for mutual competitive inhibition between beta-alanine and L-alanine; and it was also demonstrated that a process contributes to the influx of L-alanine, which is characterized by a maximum rate of transport equal to that of beta-alanine and a Kt, which is equal to the Ki of L-alanine against the influx of beta-alanine. In the concentration range 0.01 to 0.125 mM the influx of L-alanine was found to be linearly related to the concentration indicating a significant unstirred layer influence on present and previous estimates of the Kt values for influx of amino acids across the brush-border membrane of intact intestinal epithelia.
D000409:Alanine / Q000378:metabolism*; D000818:Animals; D001667:Binding, Competitive; D001692:Biological Transport; D002352:Carrier Proteins / Q000378:metabolism*; D005260:Female; D007082:Ileum / Q000378:metabolism*; D007700:Kinetics; D008871:Microvilli / Q000378:metabolism; D011817:Rabbits; D015091:beta-Alanine / Q000378:metabolism*
D002352:Carrier Proteins; D015091:beta-Alanine; D000409:Alanine