Korean J Physiol Pharmacol.  1997 Apr;1(2):185-193.

Functional characteristics of neutral amino acid transporter in opossum kidney (OK) cells

• Woo JS
• Park MH
• Oh SO
• Jung JS
• Kim YK
• Lee SH

Abstract

The characteristics of Na+/-dependent cycloleucine uptake was investigated in OK cells with regard to substrate specificity and regulation by protein kinase C (PKC). Inhibition studies with different synthetic and natural amino acids showed a broad spectrum affinity to neutral amino acids regardless of their different side chains including branched or aromatic, indicating that the Na+/-dependent cycloleucine uptake in OK cells is mediated by System B-o or System B degree -like transporter rather than the classical System A or ASC. Phorbol 12-myristate 13-acetate (PMA) and phorbol 12,13-dibutyrate, but not 4 alpha-PMA elicited a time-dependent biphasic stimulation of Na+/-dependent cycloleucine uptake, which produced early transient peak at 30 min and late sustained peak at 180 min. Both the early and late stimulations by PMA were due to an increase in Vmax and not due to a change in Km. PKC inhibitors blocked both the early and late stimulation by PMA, while protein synthesis inhibitors blocked the late stimulation only. These results suggest the existence and regulation by PKC of System B degree or System B degree -like broad spectrum transport system for neutral amino acids in OK cells.

Keyword

Neutral amino acid transport; Opossum kidney cells; System

MeSH Terms

Amino Acid Transport Systems*
Amino Acids
Amino Acids, Neutral
Cycloleucine
Kidney*
Opossums*
Phorbol 12,13-Dibutyrate
Protein Kinase C
Protein Synthesis Inhibitors
Substrate Specificity
Amino Acid Transport Systems
Amino Acids
Amino Acids, Neutral
Cycloleucine
Phorbol 12,13-Dibutyrate
Protein Kinase C
Protein Synthesis Inhibitors