Purification and properties of a peptic heme peptide from cytochrome c1.

Highly purified mouse liver plasma membranes have been used to define the properties of an NADH dehydrogenase activity associated with plasma membrane. The NADH indophenol reductase activity is two-fold stimulated at 5 × 10^?8 M glucagon and the stimulation is inhibited by atebrin. Corresponding activity in endoplasmic reticulum is not stimulated by glucagon. The NADH indophenol reductase is 90% inhibited by insulin at 7 × 10^?11M and shows a return to the original activity at higher insulin concentrations. NADH dehydrogenase activity in endoplasmic reticulum is inhibited up to 50% by insulin at a similar concentration. Triiodothyronine at 10^?7M also inhibits the plasma membrane dehydrogenase whereas thyroxine has little effect. The response of this dehydrogenase to hormones suggests a role in regulation of cellular function.