REGULATION OF ENKEPHALIN CONVERTASE--CARBOXYPEPTIDASE E

Project: Research project

Project Details

Description

Peptide neurotransmitters and hormones regulate many
physiological processes. In order to understand the mechanisms
governing the production of these neuropeptides, it is necessary
to study the enzymes involved in neuropeptide biosynthesis.
Most neuropeptides are initially synthesised as precursor proteins
that are subsequently cleaved at specific amino acid residues to
produce the bioactive peptides. Many of the proteolytic
cleavage sites are pairs of basic amino acids, and the sequential
actions of trypsin-like and carboxypeptidase B-like enzymes
would produce the neuropeptide. 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 tissue
distribution of carboxypeptidase E (CPE) suggests that this
enzyme is involved in the production of many diverse
neuropeptides. CPE has been previously characterized and
purified to homogeneity from bovine brain, pituitary, and adrenal
(Fricker and Synder, 1983). Recently, cDNA clones encoding
CPE have been isolated and sequenced from a bovine pituitary
cDNA library (Fricker, et al, 1986). The predicted amino acid
sequence suggests that CPE is initially synthesized as a
precursor protein, which must be enzymatically processed to
produce the active form of CPE. Furthermore, there are several
pairs of basic amino acids within CPE, which are similar to the
cleavage sites within neuropeptide precursors. Cleavage at
these pairs of basic amino acids could give rise to different
forms of the protein.

The objectives of this study will be to examine the control of
CPE activity at several levels. Antibodies to CPE will be used
to quantitate levels of CPE, the CPE precursor (proCPE), and
any other forms of the protein. Enzymes that process CPE, such
as the enzyme that converts proCPE to CPE, will be isolated and
characterized. Treatments that have been reported to alter
neuropeptide biosynthesis will be examined for an effect on the
levels of CPE mRNA, enzymatic activity, and different protein
forms in both cell culture and in vivo systems. Finally, the
structure of the rat CPE gene will be determined, and the 5'
region will be sequenced. This, together with the regulation
studies, will provide a background for future studies
investigating the regulatory and/or promoter elements of the
CPE gene.
StatusFinished
Effective start/end date12/31/894/30/17

ASJC

  • Biochemistry
  • Genetics
  • Cell Biology
  • Endocrine and Autonomic Systems
  • Psychiatry and Mental health
  • Medicine(all)
  • Physiology
  • Neuroscience(all)

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