REGULATION OF CARBOXYPEPTIDASE E (ENKEPHALIN CONVERTASE)

Project: Research project

Project Details

Description

Peptide neurotransmitters and hormones regulate many physiological
processes, and may be involved with the biological mechanisms underlying
drug addiction. In order to fully understand the regulation of the
biosynthesis of this important group of intercellular messengers, it is
necessary to study the enzymes responsible for neuropeptide production.
Most neuropeptides are initially synthesized as precursor proteins that are
subsequently cleaved at specific amino acid residues to produce the
bioactive peptides. These studies will focus on the neuropeptide processing
enzyme carboxypeptidase E (EC 3.4.17.10), which has been alternatively
designated carboxypeptidase H and enkephalin convertase. This enzyme
removes C-terminal basic amino acids from a wide range of neuropeptide
precursors which is an essential step for the generation of many
biologically active peptides. The rime distribution of carboxypeptidase E
(CPE) suggests that this enzyme is involved in the production of many
peptide hormones and neurotransmitters. CPE has been previously
characterized and purified to homogeneity from bovine brain, pituitary, and
adrenal (Fricker and Snyder, 1983). Several forms of CPE exist, including
both soluble and membrane bound forms. cDNA clones encoding bovine and rat
CPE have been isolated and sequenced (Fricker, et al, 1986 and 1989). The
predicted amino acid sequence indicates that CPE is initially produced as a
precursor ('proCPE'), which is posttranslationally processed into the
soluble and membrane forms of CPE.

The overall objective of these studies is to examine the mechanisms by
which CPE is regulated. In cell culture systems, various treatments will be
examined for an effect on the levels of CPE mRNA and enzymatic activity
(both soluble and membrane-bound). Since membrane-bound CPE is less
enzymatically active than the soluble form (Fricker, 1988), the processing
of CPE is a potential mechanism for regulating CPE activity. The
post-translational modification responsible for the difference between the
soluble and membrane-bound forms of CPE will be determined, and the enzymes
that proteolytically process proCPE into the various forms of CPE will be
identified and characterized. Finally, the 5'-flanking region of the rat
CPE gene will be sequenced, and the enhancer and/or promoter elements that
confer the tissue-specific expression of CPE will be determined. The
results of this multi-level analysis will provide a better understanding of
the mechanisms responsible for the regulation of CPE expression and
activity.
StatusFinished
Effective start/end date8/1/907/31/91

Funding

  • NATIONAL INSTITUTE ON DRUG ABUSE

ASJC

  • Molecular Biology
  • Biophysics
  • Biochemistry
  • Biotechnology
  • Microbiology

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