Glycine transport by cultured human fibroblasts.
The transport of glycine was studied in cultured human fibroblasts. The amino acid entered the cell by Na+-dependent and Na+-independent mechanisms. Na+-independent glycine (0.1 mM) transport was less than 10% of total uptake and occurred by a mechanism formally indistinguishable from diffusion. Two distinct routes contributed to Na+-dependent glycine transport. The first route was identified with system A because it was inhibited by MeAIB and underwent adaptive regulation. The second route was identified with system ASC as it was inhibited by L-alanine, but not by MeAIB. Kinetic analysis revealed that the two systems operated glycine transport with the same Km of 1.6 mM, a value unusually high for system ASC.
Longo
N
N
Istituto di Patologia Generale, Università di Parma, Italy.
Franchi-Gazzola
R
R
Bussolati
O
O
Dall'Asta
V
V
Nucci
F A
FA
Spisni
A
A
Gazzola
G C
GC
D000328:Adult; D000621:Aminoisobutyric Acids / Q000494:pharmacology; D001692:Biological Transport / Q000187:drug effects; D002478:Cells, Cultured; D003470:Culture Media; D003513:Cycloheximide / Q000494:pharmacology; D005347:Fibroblasts / Q000378:metabolism*; D005998:Glycine / Q000378:metabolism*; D006801:Humans; D007700:Kinetics
D000621:Aminoisobutyric Acids; D003470:Culture Media; C017911:2-(methylamino)isobutyric acid; D003513:Cycloheximide; D005998:Glycine