L-lysine transport in chicken jejunal brush border membrane vesicles.
The properties of l-lysine transport in chicken jejunum have been studied in brush border membrane vesicles isolated from 6-wk-old birds. l-lysine uptake was found to occur within an osmotically active space with significant binding to the membrane. The vesicles can accumulate l-lysine against a concentration gradient, by a membrane potential-sensitive mechanism. The kinetics of l-lysine transport were described by two saturable processes: first, a high affinity-transport system (KmA = 2.4 +/- 0.7 micromol/L) which recognizes cationic and also neutral amino acids with similar affinity in the presence or absence of Na+ (l-methionine inhibition constant KiA, NaSCN = 21.0 +/- 8.7 micromol/L and KSCN = 55.0 +/- 8. 4 micromol/L); second, a low-affinity transport mechanism (KmB = 164. 0 +/- 13.0 micromol/L) which also recognizes neutral amino acids. This latter system shows a higher affinity in the presence of Na+ (KiB for L-methionine, NaSCN = 1.7 +/- 0.3 and KSCN = 3.4 +/- 0.9 mmol/L). L-lysine influx was significantly reduced with N-ethylmaleimide (0.5 mmol/L) treatment. Accelerative exchange of extravesicular labeled l-lysine was demonstrated in vesicles preloaded with 1 mmol/L l-lysine, l-arginine or l-methionine. Results support the view that l-lysine is transported in the chicken jejunum by two transport systems, A and B, with properties similar to those described for systems b0,+ and y+, respectively.
Torras-Llort
M
M
Unitat de Fisiologia, Facultat de Farmàcia, Universitat de Barcelona, E-08028 Barcelona, Spain.
Ferrer
R
R
Soriano-García
J F
JF
Moretó
M
M
D000818:Animals; D001120:Arginine / Q000494:pharmacology; D001692:Biological Transport / Q000187:drug effects; D002645:Chickens; D005033:Ethylmaleimide / Q000494:pharmacology; D005947:Glucose / Q000378:metabolism; D007583:Jejunum / Q000378:metabolism*; D007700:Kinetics; D008239:Lysine / Q000378:metabolism*; D008297:Male; D008715:Methionine / Q000494:pharmacology; D008871:Microvilli / Q000187:drug effects / Q000378:metabolism*; D008954:Models, Biological; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D013393:Sucrase; D013861:Thiocyanates / Q000494:pharmacology
D013861:Thiocyanates; C024553:sodium thiocyanate; D001120:Arginine; D008715:Methionine; D013393:Sucrase; D000254:Sodium-Potassium-Exchanging ATPase; D005947:Glucose; D008239:Lysine; D005033:Ethylmaleimide; C009941:potassium thiocyanate