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The hypothesis of a preferential biosynthesis of a major phenobarbital inducible form of hepatic cytochrome P-450 (P-450b) in mitochondria-associated rough endoplasmic reticulum (RERmito) was tested by measuring incorporation rates of [35S]methionine and delta-amino[3H]levulinate into the hemoprotein in adult rats. RERmito, rough microsomes (RM representing RER not associated with mitochondria) and smooth microsomes (SM) were quantitatively isolated from the same homogenate by rate zonal centrifugation and their content of P-450b determined by rocket immunoelectrophoresis. P-450b was isolated by immunoprecipitation from detergent-solubilized membrane fractions. The time course and rate of incorporation of [35S] methionine into immunoprecipitable P-450b of RERmito and of RM were similar at all time points studied (2-15 min) both under conditions of maximal induction (4 injections of phenobarbital in 4 days) and after a single injection of phenobarbital. The incorporation of [35S]methionine into P-450b of SM was slower at early time points (2-8 min) but similar to RERmito and RM after 15 min. In contrast, at short labeling periods (less than 8 min) more delta-amino[3H]levulinate was incorporated into P-450b of RERmito than into P-450b of RM and SM. No significant accumulation of free apocytochrome P-450b was found in either membrane fraction. These data indicate a close coordination of the biosynthesis and assembly of apocytochrome P-450b and its prosthetic heme but do not support the hypothesis of a major functional role of MITO X RER complexes in the synthesis of microsomal cytochrome P-450b.
P J Meier, and
R Gasser, and
H P Hauri, and
B Stieger, and
U A Meyer
March 1981,
Experimental cell research,
P J Meier, and
R Gasser, and
H P Hauri, and
B Stieger, and
U A Meyer
February 1981,
Biokhimiia (Moscow, Russia),
P J Meier, and
R Gasser, and
H P Hauri, and
B Stieger, and
U A Meyer
August 1982,
The Anatomical record,
P J Meier, and
R Gasser, and
H P Hauri, and
B Stieger, and
U A Meyer
January 1993,
Sub-cellular biochemistry,
P J Meier, and
R Gasser, and
H P Hauri, and
B Stieger, and
U A Meyer
September 1980,
The Biochemical journal,
P J Meier, and
R Gasser, and
H P Hauri, and
B Stieger, and
U A Meyer
November 1979,
Biochemical and biophysical research communications,
P J Meier, and
R Gasser, and
H P Hauri, and
B Stieger, and
U A Meyer
July 1977,
The Journal of biological chemistry,
P J Meier, and
R Gasser, and
H P Hauri, and
B Stieger, and
U A Meyer
June 1979,
FEBS letters,
P J Meier, and
R Gasser, and
H P Hauri, and
B Stieger, and
U A Meyer
August 1981,
Biochimica et biophysica acta,
P J Meier, and
R Gasser, and
H P Hauri, and
B Stieger, and
U A Meyer
January 1978,
Methods in enzymology,
