title: Rotation and interactions of genetically expressed cytochrome P-450IA1 and NADPH-cytochrome P-450 reductase in yeast microsomes.
abstract: Rat liver cytochrome P-450IA1 and/or yeast NADPH-cytochrome P-450 reductase was expressed genetically in yeast microsomes. The ratio of P-450IA1 to the reductase was about 17:1 and 1:2 without and with coexpression of the reductase, respectively. Rotational diffusion of P-450IA1 was examined by observing the flash-induced absorption anisotropy, r(t), of the heme.CO complex. In only P-450IA1-expressed microsomes, 28% of P-450IA1 was rotating with a rotational relaxation time (phi) of about 1200 microseconds. The mobile population was increased to 43% by the presence of the coexpressed reductase, while phi was not changed significantly. Increased concentration of KCl from 0 to 1000 mM caused considerable mobilization of P-450IA1. The results demonstrate a proper incorporation of P-450IA1 molecules into yeast microsomal membranes. The significant mobilization of P-450IA1 by the presence of reductase suggests a possible transient association of P-450IA1 with the reductase.
authors.affiliation: Institute of Physics, College of Arts and Sciences, University of Tokyo, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Iwase
authors.forename: T
authors.initials: T
authors.lastname: Sakaki
authors.forename: Y
authors.initials: Y
authors.lastname: Yabusaki
authors.forename: H
authors.initials: H
authors.lastname: Ohkawa
authors.forename: Y
authors.initials: Y
authors.lastname: Ohta
authors.forename: S
authors.initials: S
authors.lastname: Kawato
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology; D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry* / Q000235:genetics; D005454:Fluorescence Polarization; D005822:Genetic Vectors; D008861:Microsomes / Q000201:enzymology*; D008862:Microsomes, Liver / Q000201:enzymology; D009251:NADPH-Ferrihemoprotein Reductase / Q000737:chemistry* / Q000187:drug effects / Q000235:genetics; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D011995:Recombination, Genetic; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics
chemical_list: D011189:Potassium Chloride; D003577:Cytochrome P-450 Enzyme System; D009251:NADPH-Ferrihemoprotein Reductase