... PAT1 are in the range of 1 15 mM[2,7,9 ,10 ]. PAT1 recognizes, besidesL -a aminoacids, a number of additional substrates, e .g. b-alanine,c-aminobutyrate (GABA), betaine,D-Ser, and D-Ala [1, 2,5,6,9], ... but also osmolytes such as sarcosine and betaine, and theD-enantiomers of serine and alanine. Theapparent affinities of PAT1 substrates are mainly in therange of 2 15 mM [1, 2,4,6,9]. As shown ... (10 0 lM) was measured at pH 6.5 for 10 min in the presence of unlabeled amino acids and derivatives at a fixed concentration of 10 mMandaregivenaspercentageinhibitionofthecontroluptakemeasuredintheabsenceofinhibiton.Data...