title: Density regulation of amino acid transport in cultured, androgen-responsive tumor cells.
abstract: In androgen-responsive cells, activity of a sodium-dependent transport system for neutral amino acids is shown to be density-dependent, whereas activity of a sodium-independent system is not.  Transport of the non-metabolizable amino acids, alpha-aminoisobutyric acid )alpha-aib) was largely sodium-dependent, wherease transport of cycloleucine (cyleu) was by  both sodium-dependent and sodium-independent systems.  The km for cyleu transport changed with density because only the sodium-dependent portion of this transport was density-dependent.  By contrast, the Vmax for alpha-aib transport changed with density, indicating that either amount of functional membrane carrier of the activity of the sodium pump was affected.
mesh_terms: D000596:Amino Acids / Q000378:metabolism*; D000621:Aminoisobutyric Acids / Q000378:metabolism*; D001693:Biological Transport, Active / Q000187:drug effects; D002452:Cell Count; D002460:Cell Line; D003515:Cycloleucine / Q000378:metabolism*; D007700:Kinetics; D012964:Sodium / Q000378:metabolism; D013739:Testosterone / Q000494:pharmacology*
chemical_list: D000596:Amino Acids; D000621:Aminoisobutyric Acids; D003515:Cycloleucine; D013739:Testosterone; D012964:Sodium