Characteristics and adaptive regulation of glycine transport in cultured glial cells.
The transport of glycine in C6 glioma cells takes place mainly in a heterogeneous Na+-dependent manner which can be resolved into different components. A Na+- and Cl(-)-dependent component with high affinity for glycine is pH-sensitive and inhibited by sarcosine, all these characteristics corresponding to System Gly. The low-affinity component of the transport of glycine can be discriminated as two components, namely System A and System ASC. The main proportion of glycine transport through the low-affinity system is carried out by the ASC System, which appears to be constitutively expressed by the cells. The adaptive response of the low-affinity Na+-dependent transport of glycine to amino acid deprivation was identified with System A on the basis of its ion-dependency, pH-sensitivity and by inhibition analysis. The possible physiological role of the high- and low-affinity components of the transport system for glycine in glial cells is discussed.
Zafra
F
F
Centro de Biología Molecular, Facultad de Ciencias, Universidad Autónoma de Madrid, Spain.
Giménez
C
C
D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D001692:Biological Transport; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D005910:Glioma / Q000378:metabolism; D005998:Glycine / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D051381:Rats; D012964:Sodium / Q000378:metabolism; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000378:metabolism*
D000596:Amino Acids; D003609:Dactinomycin; D003513:Cycloheximide; D012964:Sodium; D005998:Glycine