Generation of diversity and evolution of opioid peptides.
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Adrenal Medulla↗
Biomedical subjects
M Comb
Publications and source records attributed to M Comb.
Primary structure of the human Met- and Leu-enkephalin precursor and its mRNA.
The nucleotide sequence of a complete cDNA copy of enkephalin precursor mRNA from human phaeochromocytoma is reported. The corresponding amino acid sequence shows that the precursor is 267 amino acids long and contains six interspersed Met-enkephalin sequences and one Leu-enkephalin sequence. Five of the seven enkephalins are flanked on both sides by pairs of basic amino acid residues. The precursors does not contain the sequences of the opioid peptides, dynorphin, alpha-neo-endorphin or beta-endorphin.
Amino Acid Sequence↗
Partial characterization of the mRNA that codes for enkephalins in bovine adrenal medulla and human pheochromocytoma.
[Met]enkephalin and [Leu]enkephalin are derived from a protein in bovine adrenal medulla that contains multiple copies of [Met]enkephalin [Kilpatrick, D. L., Taniguchi, T., Jones, B. N., Stern, A. S., Shively, J. E., Hullihan, J., Kimura, S., Stein, S. & Udenfriend, S. (1981) Proc. Natl. Acad. Sci. USA 78, 3265--3268.] Here we characterize pro-enkephalin mRNA from bovine and human tissue by use of an oligodeoxynucleotide pentadecamer probe complementary to codons for Tyr-Gly-Gly-Phe-Met ([Met]enkephalin). This probe hybridizes specifically to a species of poly(A)-RNA from adrenal medulla and human pheochromocytoma, (1400--1450 bases), and also to [Met]enkephalin-containing pro-opiomelanocortin mRNAs from bovine pituitary (1200 bases) and from mouse pituitary tumor cell (1100 bases). A cloned cDNA probe (144 bases) complementary to the region of pro-opiomelanocortin mRNA that codes for lipotropin does not hybridize to the RNA from bovine adrenal medulla, demonstrating that the latter RNA is not pro-opiomelanocortin mRNA. The pentadecamer probe was extended to make cDNA with reverse transcriptase after hybridizing it to adrenal poly(A)-RNA. The sequence of an extended cDNA, 62 bases in length, was found to correspond exactly to that expected from the amino acid sequence of peptide E (a bovine adrenal peptide containing [Met]- and [Leu]enkephalin sequences). This cDNA also forms a specific hybrid with the RNA from bovine adrenal and human pheochromocytoma, confirming that these species of RNA are pro-enkephalin mRNA.
Adrenal Gland Neoplasms↗
Nucleotide sequence of the chi recombinational hot spot chi +D in bacteriophage lambda.
Chi sites in bacteriophage lambda stimulate recombination promoted by the RecBC pathway of Escherichia coli. Mutations which create these sites occur at four widely separated loci in lambda. We report here the nucleotide sequence surrounding the site of one of these loci, chi D, located near the S gene. The mutations creating the active Chi site, designated chi +D, are transversions from CG to AT. This mutation, like the chi +B and chi +C mutations previously analyzed, leads to a nucleotide sequence common to all three active chi sites.
Bacteriophage lambda↗
Regulation of opioid gene expression.
Opioid peptides are synthesized in the form of large precursors, which contain the information for more than one biologically active peptide. Using recombinant DNA technology, three opioid precursors have been sequenced: pro-opiomelanocortin (POMC), proenkephalin and prodynorphin. Analysis of the structures of these three precursors and their corresponding genes show striking similarities suggesting a common evolutionary mechanism. Regulation of POMC gene expression has been analyzed in different rat tissues. Detection of POMC mRNA in brain tissues supports the hypothesis that ACTH and endorphin peptides are synthesized in these tissues. Quantitation of POMC mRNA levels in pituitaries of rats subjected to adrenalectomy and glucocorticoid treatment shows that the feedback effect of the glucocorticoids occurs at the level of the rate of transcription of POMC mRNA.
Adrenalectomy↗
A cyclic AMP- and phorbol ester-inducible DNA element.
Many cellular processes are regulated by hormones and neurotransmitters which interact with cell-surface receptors to produce intracellular second messengers that activate protein kinases. Cyclic (c) AMP is a second messenger whose intracellular level is determined by receptor-mediated activation or inhibition of adenylate cyclase. Phorbol esters directly activate protein kinase C, a Ca2+ and phospholipid-dependent protein kinase and a component of a different second messenger system, the phosphatidylinositol pathway. Proenkephalin messenger RNA levels are regulated in response to cAMP analogues, activators of adenylate cyclase, nicotinic agonists and depolarization, suggesting that expression of the gene encoding proenkephalin is regulated by trans-synaptic events involving cell-surface-receptor activation. Here we report that cAMP analogues and activators of adenylate cyclase regulate a proenkephalin-chloramphenicol acetyl transferase fusion gene when transiently expressed in tissue culture cells. Phorbol ester regulates the fusion gene in a similar fashion, but requires the presence of phosphodiesterase inhibitors for large effects. The DNA sequences required for regulation by both cAMP and phorbol ester map to the same 37-base pair (bp) region located 107-71 bp 5' to the mRNA cap site of the proenkephalin gene. This highly conserved region is composed of three closely related 12-bp sequences and has properties similar to those of previously characterized transcriptional enhancers.
Acetyltransferases↗