Density regulation of amino acid transport in cultured, androgen-responsive tumour cells.
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 acid, alpha-aminoisobutyric acid (alpha-aib) was largely sodium-dependent, whereas 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 the amount of functional membrane carrier or the activity of the sodium pump was affected.
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*
D000596:Amino Acids; D000621:Aminoisobutyric Acids; D003515:Cycloleucine; D013739:Testosterone; D012964:Sodium