Sequence of a novel cytochrome CYP2B cDNA coding for a protein which is expressed in a sebaceous gland, but not in the liver.
The major phenobarbital-inducible rat hepatic cytochromes P-450, CYP2B1 and CYP2B2, are the paradigmatic members of a cytochrome P-450 gene subfamily that contains at least seven additional members. Specific oligonucleotide probes for these genomic members of the CYP2B subfamily were used to assess their tissue-specific expression. In Northern-blot analysis a probe specific to gene 4 (which is designated now as CYP2B12) hybridized to a single mRNA present in the preputial gland, an organ which is used as a model for sebaceous glands, but did not hybridize to mRNA isolated from the liver or from five other tissues of untreated or Aroclor 1254-treated rats. The cDNA sequence for the CYP2B12 RNA was determined from overlapping cDNA clones and contained a long open reading frame of 1476 bp. The nucleotide sequence of the CYP2B12 cDNA was 85% similar to the sequence of the CYP2B1 cDNA in its coding region and was different from any CYP2B cDNA characterized until now. The cDNA-derived primary structure of the CYP2B12 protein contains a signal sequence for its insertion into the endoplasmic reticulum and the putative haem-binding site characteristic of cytochromes P-450. A part of the potential haem pocket of CYP2B12 was identical with a similar structure in a bacterial protocatechuate dioxygenase. In immunoblot analysis of preputial-gland microsomes, antibodies against CYP2B1 recognized a single abundant protein with a lower apparent molecular mass than that of CYP2B1. Our results demonstrate that the CYP2B12 protein has the potential to be enzymically active and are the first demonstration that a member of the CYP2B subfamily is expressed exclusively and at high levels in an extrahepatic organ.
Friedberg
T
T
Institute of Toxicology, University of Mainz, Germany.
Grassow
M A
MA
Bartlomowicz-Oesch
B
B
Siegert
P
P
Arand
M
M
Adesnik
M
M
Oesch
F
F
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics* / Q000378:metabolism; D004247:DNA; D005260:Female; D008099:Liver / Q000201:enzymology*; D008297:Male; D008861:Microsomes / Q000201:enzymology; D008862:Microsomes, Liver / Q000201:enzymology; D008969:Molecular Sequence Data; D005810:Multigene Family; D015345:Oligonucleotide Probes; D051381:Rats; D017207:Rats, Sprague-Dawley; D012259:Ribonuclease, Pancreatic / Q000378:metabolism; D012627:Sebaceous Glands / Q000201:enzymology*; D015719:Single-Strand Specific DNA and RNA Endonucleases / Q000378:metabolism
D015345:Oligonucleotide Probes; D004247:DNA; D003577:Cytochrome P-450 Enzyme System; D012259:Ribonuclease, Pancreatic; D015719:Single-Strand Specific DNA and RNA Endonucleases