JBC, Vol. 252, Issue 3, 950-954, Feb, 1977
Regulation of 3-hydroxy-3-methylglutaryl coenzyme a reductase in minimal deviation hepatoma 7288C. Immunological measurements in hepatoma tissue culture cells
O. R. Beirne, R. Heller and J. A. Watson
The mechanism of action of serum lipoproteins and 25-hydroxycholesterol on
3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase activity in
hepatoma tissue culture (HTC) cells was investigated using antiserum
against purified rat liver HMG-CoA reductase (Heller, R. A., and
Shrewsbury, M. A. (1976)J. Biol. Chem. 251, 3815-3822). This antiserum
cross-reacted with solubilized and membrane-bound HMG-CoA reductase from
HTC cells. The enzymes from rat liver and HTC cells appeared antigenically
identical. The increase in HMG-CoA reductase activity of HTC cells grown in
medium which lacked serum lipoproteins was shown to be due to an increase
in immunoprecipitable enzyme. In contrast, the 25-hydroxycholesterol
suppression of reductase activity leads to a reduction in the antigenicity
of the enzyme rather than a decrease in its number of molecules.