Functional characteristics of neutral amino acid transporter in opossum kidney (OK) cells.
- Author:
Jae Suk WOO
1
;
Moon Hwan PARK
;
Sae Ok OH
;
Jin Sup JUNG
;
Yong Keun KIM
;
Sang Ho LEE
Author Information
1. Department of Physiology, College of Medicine, Pusan National University, Ami-Dong 1-10, Suh-Ku, Pusan 602-739 South Korea.
- Publication Type:Original Article
- Keywords:
Neutral amino acid transport;
Opossum kidney cells;
System
- MeSH:
Amino Acid Transport Systems*;
Amino Acids;
Amino Acids, Neutral;
Cycloleucine;
Kidney*;
Opossums*;
Phorbol 12,13-Dibutyrate;
Protein Kinase C;
Protein Synthesis Inhibitors;
Substrate Specificity
- From:The Korean Journal of Physiology and Pharmacology
1997;1(2):185-193
- CountryRepublic of Korea
- Language:English
-
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.
