Cytochrome P-420: tubular aggregated from hepatic microsomes.

Aggregates were formed when clear supernatants from hepatic microsomes that had been treated with steapsin were desalted and concentrated. These aggregates contain large numbers of uniform tubular elements. These structures resemble microtubules seen in many cells but differ in their substructure. The aggregates were rich in cytochrome P-420. Unlike soluble cytochrome P-420, the cytochrome P-420 contained in the aggregates combines with drugs to give the characteristic difference spectra normally seen only with cytochrome P-450 contained in intact microsomes.