Clonal Differences in Glutamine Synthetase Activity of Hepatoma Cells

Most hepatomas contain only traces of glutamine synthetase (GS) although they originate from liver which has high levels of the enzyme (1-3) The H T C cell line which was derived from Morris Hepa toma 7288C retained certain characteristics of liver cells, notably the induction of tyrosine amino transferase (4, 5), while other liver characteristics, among them GS activity, could not be detected I Since H T C cells in culture apparently required glutamine for growth 1, the question arose whether the genetic information necessary for the synthesis of GS was absent or was present but for some reason was not expressed The present report shows that clones which produce glutamine synthetase and can survive without glutamine can be isolated from the H T C cell populat ion Some of the properties of these clones are outlined