title: Characteristics of a neutral amino acid transport system (system A) in osteoblastic rat osteosarcoma cells.
abstract: Transport of alpha-aminoisobutyric acid (AIB) in the clonal, osteoblastic-like cell line, ROS 17/2, was characterized. AIB transport was time-, temperature- and Na+-dependent. Both ouabain and monensin inhibited AIB transport in these cells. AIB uptake followed Michaelis-Menten kinetics with an apparent Km = 0.57 mM and a Vmax = 4.07 nmol/30 min/plate. These characteristics are consistent with the presence of system A neutral amino acid transport in ROS 17/2 cells. Exposure of ROS 17/2 cells to either parathyroid hormone or dibutyryl cyclic AMP (db-cAMP), but not to dibutyryl cyclic GMP (db-cGMP), markedly stimulated AIB transport. This suggests that extracellular stimuli which enhance osteogenic responses in this cell type, coordinately upregulate system A transport.
authors.forename: B J
authors.initials: BJ
authors.lastname: Baum
authors.forename: A
authors.initials: A
authors.lastname: Shteyer
mesh_terms: D000621:Aminoisobutyric Acids / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002250:Carbon Radioisotopes; D007700:Kinetics; D012516:Osteosarcoma / Q000378:metabolism*; D051381:Rats; D012964:Sodium / Q000494:pharmacology
chemical_list: D000621:Aminoisobutyric Acids; D002250:Carbon Radioisotopes; C100049:2-aminoisobutyric acid; D012964:Sodium