Characteristics of a neutral amino acid transport system (system A) in osteoblastic rat osteosarcoma cells |
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| Authors: | Bruce J Baum Arie Shteyer |
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| Institution: | 1. Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085, India;2. Radiation Biology & Health Sciences Division, Bhabha Atomic Research Centre, Mumbai 400 085, India;3. Homi Bhabha National Institute, Anushaktinagar, Mumbai 400 094, India;4. Sunandan Divatia School of Science, SVKM''s NMIMS, Mumbai 400 056, India;1. Department of Engineering, Aarhus University, DK-8000 Aarhus C, Denmark;2. Institute of Basic Theory for Chinese Medicine, China Academy of Chinese Medicine Science, China;3. Interdisciplinary Nanoscience Center (iNANO), Aarhus University, DK-8000 Aarhus C, Denmark;4. Institute of Biomedicine, Aarhus University, Wilhelm Meyers Allé 4, DK-8000 Aarhus C, Denmark |
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| 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. |
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