Effect of concanavalin A on tyrosine aminotransferase in rat hepatoma tissue culture cells. Rapid reversible inactivation of soluble enzyme.
Concanavalin A added to intact cells at 37 degrees caused rapid and reversible inactivation of a soluble enzyme, tyrosine aminotransferase, in two lines of rat hepatoma tissue culture cells grown in monolayer culture. This temperature-dependent process was independent of de novo protein and RNA synthesis and independent of increased uptake of Ca2+ and Mg2+ or glucose. The inactivation could be reversed by adding alpha-methyl-D-mannopyranoside a competing sugar for concanavalin A binding. Other lectins known to bind to different sugars did not bring about the inactivation of tyrosine aminotransferase. Addition of concanavalin A did not result in the inactivation of another soluble enzyme, lactic dehydrogenase. The maintenance of tyrosine aminotransferase in an inactive form after the binding of concanavalin A to the cells required the continued presence of concanavalin A. This effect of concanavalin A could not be mimicked either by dibutyryl cyclic adenosine or guanosine monophosphoric acid. Incubation of cell extracts with concanavalin A did not result in inactivation nor did mixing of extracts from concanavalin A-treated cells with extracts from untreated cells. On the basis of these results we conclude that the following are the essential requirements for concanavalin A to bring about the inactivation of tyrosine aminotransferase: (a) the binding of native concanavalin A to the cells; (b) integrity of certain structural elements of the cells.
D000410:Alanine Transaminase / Q000378:metabolism; D000818:Animals; D006528:Carcinoma, Hepatocellular / Q000201:enzymology*; D002460:Cell Line; D003208:Concanavalin A / Q000031:analogs & derivatives; D000242:Cyclic AMP / Q000494:pharmacology; D006152:Cyclic GMP / Q000494:pharmacology; D004790:Enzyme Induction / Q000187:drug effects; D005472:Fluorouracil / Q000494:pharmacology; D007700:Kinetics; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008113:Liver Neoplasms; D051381:Rats; D013806:Theophylline / Q000494:pharmacology; D014444:Tyrosine Transaminase / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism*
D003208:Concanavalin A; D013806:Theophylline; D000242:Cyclic AMP; D007770:L-Lactate Dehydrogenase; D000410:Alanine Transaminase; D014444:Tyrosine Transaminase; D006152:Cyclic GMP; D005472:Fluorouracil