Rat preprocarboxypeptidase H. Cloning, characterization, and sequence of the cDNA and regulation of the mRNA by corticotropin-releasing factor.
Carboxypeptidase H is a putative post-translational processing enzyme which removes basic amino acid residues from intermediates during protein hormone biosynthesis. A 2.2-kilobase pair cDNA was shown to contain the complete amino acid sequence of rat carboxypeptidase H. The deduced amino acid sequence revealed that the enzyme was synthesized as preprocarboxypeptidase H, a precursor form of 476 amino acid residues. Preprocarboxypeptidase H contained a putative hydrophobic signal peptide and a short propeptide which contained 5 adjacent Arg residues at its C terminus. Northern blot analysis identified a single carboxypeptidase H mRNA of approximately 2.3 kilobases in brain, pituitary, and heart, as well as in mouse AtT20 cells. No carboxypeptidase H mRNA was detected in rat liver, spleen, kidney, lung, and mammary gland. Sequence analysis of cDNAs obtained from different rat tissues suggested that a single mRNA encodes an identical carboxypeptidase in several tissues. Treatment of AtT20 cells with dexamethasone decreased the levels of both carboxypeptidase H and preproopiomelanocortin (POMC) mRNAs by approximately 30%. Exposure of the dexamethasone-treated cells to corticotropin-releasing factor effected a 2- to 3-fold increase in the carboxypeptidase H and POMC mRNA levels relative to those of dexamethasone-treated cells exposed to control medium. This suggests that the mRNA levels of POMC and one of its putative post-translational processing enzymes, carboxypeptidase H, are co-regulated by corticotropin-releasing factor and steroid hormones.
Rodríguez
C
C
Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907.
Brayton
K A
KA
Brownstein
M
M
Dixon
J E
JE
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D002268:Carboxypeptidases / Q000235:genetics*; D003001:Cloning, Molecular; D003346:Corticotropin-Releasing Hormone / Q000494:pharmacology*; D004247:DNA / Q000235:genetics*; D004792:Enzyme Precursors / Q000235:genetics*; D005786:Gene Expression Regulation / Q000187:drug effects*; D005796:Genes; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes; D011487:Protein Conformation; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics*; D051381:Rats; D015183:Restriction Mapping
D004792:Enzyme Precursors; D015345:Oligonucleotide Probes; D012333:RNA, Messenger; D004247:DNA; D003346:Corticotropin-Releasing Hormone; D002268:Carboxypeptidases; C059040:preprocarboxypeptidase H