The induction and characterization of rat liver stearyl-CoA desaturase mRNA

Poly(A+) RNA isolated from livers of rats induced for stearyl-CoA desaturase contains elevated levels of mRNA for this enzyme which is translated in a rabbit reticulocyte system. The protein is immunologically and by peptide fingerprinting following Staphylococcus aureus V8 protease digestion identical to the isolated enzyme and, therefore, not synthesized in a detectable larger precursor form. The desaturase mRNA is selectively translated on free cytoplasmic polysomes from rat liver and represents at least a 40-fold increase in translatable mRNA in livers of induced animals. Northern blot analysis, using a cDNA probe complementary to rat liver desaturase mRNA, demonstrated that the desaturase is encoded by a 4900-base mRNA which is elevated approximately 50-fold in induced liver.