Interference of L-arginine analogues with L-arginine transport mediated by the y+ carrier hCAT-2B.
The inducible human cationic amino acid transporter hCAT-2B was expressed in Xenopus laevis oocytes, and this system was used to test the effect of several NO synthase (NOS) inhibitors and/or L-arginine analogues on L-arginine transport by this y+ carrier. L-NG-Methyl-L-arginine (L-NMA), asymmetrical L-NG, NG-dimethyl-L-arginine (L-ADMA), L-N5-(1-iminoethyl)-ornithine (L-NIO), L-NG-nitro-L-arginine (L-NNA), and L-NG-nitro-L-arginine methyl ester (L-NAME) all inhibited the inducible NOS II extracted from RAW 264.7 macrophages induced with bacterial lipopolysaccharide. L-NMA, L-ADMA, and L-NIO also competed with L-arginine for transport by hCAT-2B, whereas L-NNA and L-NAME did not. The two L-arginine analogues, symmetrical NG, NG-dimethyl-L-arginine (L-SDMA) and alpha-amino-delta-isothioureidovaleric acid (AITV), as well as L-lysine, did not block enzymatic activity of NOS II, but did compete for L-arginine transport mediated by hCAT-2B. L-Lysine and L-SDMA were transported efficiently by hCAT-2B and exchanged against intracellular L-arginine, resulting in an L-arginine depletion of the cells. AITV was a much poorer substrate of hCAT-2B and had only little effect on intracellular L-arginine concentrations. These data indicate that substrate recognition differs markedly between the inducible L-arginine transporter hCAT-2B and the inducible NOS II, with different L-arginine analogues having affinity to only one or both of these proteins.
Closs
E I
EI
Department of Pharmacology, Johannes Gutenberg University, Mainz, Germany. closs@mzdmza.zdv.uni-mainz.de
Basha
F Z
FZ
Habermeier
A
A
Förstermann
U
U
D026923:Amino Acid Transport Systems, Basic; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D001692:Biological Transport; D002352:Carrier Proteins / Q000378:metabolism*; D002460:Cell Line; D004791:Enzyme Inhibitors; D005947:Glucose / Q000378:metabolism; D051272:Glucose Transporter Type 1; D006801:Humans; D008239:Lysine / Q000494:pharmacology; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D009004:Monosaccharide Transport Proteins / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D052247:Nitric Oxide Synthase Type II; D009865:Oocytes / Q000378:metabolism; D051381:Rats; D014982:Xenopus laevis
D026923:Amino Acid Transport Systems, Basic; D002352:Carrier Proteins; D004791:Enzyme Inhibitors; D051272:Glucose Transporter Type 1; D008565:Membrane Proteins; D009004:Monosaccharide Transport Proteins; C495677:SLC2A1 protein, human; D001120:Arginine; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; C496318:Nos2 protein, rat; D005947:Glucose; D008239:Lysine