Inhibition of the lepidopteran amino acid co-transporter KAAT1 by phenylglyoxal: role of arginine 76.
Phenylglyoxal (PGO), an arginine-modifying reagent, is an irreversible inhibitor of KAAT1-mediated leucine transport, expressed in Xenopus oocytes. The PGO effect was dose-dependent and 5 mm PGO determined a V(max) reduction to 24% of the control, consistent with the covalent binding to transporter arginine residues not located in the leucine binding site. The use of labelled [(14)C]PGO confirmed that the inhibitor binds KAAT1. The protein membrane domain contains seven arginine residues one of which, arginine 76, is conserved in the family of GABA transporters. Using site-directed mutagenesis we showed that only arginine 76 is crucial for KAAT1 activity and is involved in PGO binding.
Castagna
Michela
M
Istituto di Fisiologia Generale e di Chimica Biologica, Facoltà di Farmacia, Università di Milano, Milano, Italy.
Vincenti
Sergio
S
Marciani
Paola
P
Sacchi
V Franca
VF
D026921:Amino Acid Transport Systems, Neutral; D000818:Animals; D001120:Arginine / Q000378:metabolism / Q000502:physiology*; D001692:Biological Transport / Q000502:physiology*; D002352:Carrier Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000502:physiology; D004591:Electrophoresis, Polyacrylamide Gel; D005786:Gene Expression Regulation / Q000502:physiology; D019476:Insect Proteins; D007700:Kinetics; D007915:Lepidoptera / Q000235:genetics / Q000378:metabolism*; D007930:Leucine / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000502:physiology; D016297:Mutagenesis, Site-Directed; D018408:Patch-Clamp Techniques; D010658:Phenylglyoxal / Q000494:pharmacology*; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D014982:Xenopus laevis / Q000235:genetics / Q000378:metabolism
D026921:Amino Acid Transport Systems, Neutral; D002352:Carrier Proteins; D019476:Insect Proteins; C112249:KAAT1 protein, insect; D008562:Membrane Glycoproteins; D001120:Arginine; D007930:Leucine; D010658:Phenylglyoxal