TYPE A CCK RECEPTOR STRUCTURE, FUNCTION AND REGULATION

Project: Research project

Description

With the long-term goal of better understanding the role of the
gastrointestinal peptide hormone cholecystokinin (CCK) in health and
disease, the current proposal focuses on the structure, function and
regulation of the type of CCK receptor found on classical
gastrointestinal targets such as pancreas and gallbladder, the Type A CCK
receptor. This is known to be important physiologically and is
potentially important in the pathogenesis of digestive dysfunctional
states. Our general hypothesis is that the structure of this receptor
will provide insight into the molecular basis for its initiation of
signalling cascades within the cell and for receptor regulation. We will
test the specific hypothesis that the CCK-binding subunit follows the
structural motif of other guanine nucleotide-binding protein (G-p)-
associated receptors, with seven transmembrane segments, and domains
which are glycosylated, cysteine-rich, phosphorylated, and fatty acid-
acrylated. This will be accomplished using approaches of affinity
labeling, enzymatic digestion, affinity chromatography, precursor
incorporation in biosynthesis, and purification with chemical
characterization. Unlike most G-p-coupled receptors cloned, CCK has
trophic effects on the acinar cell, suggesting the possibility of its
receptor having additional novel domains. Particular attention will be
directed toward the processes of receptor phosphorylation and fatty acid
acylation, since these have potentially profound functional and
regulatory roles. Affinity labeling probes with photolabile and
chemically-reactive moieties within the receptor binding domain will be
used to identify domains, and possibly residues, within the active site
of this receptor. Partial amino acid sequencing of some of these domains
will be performed, and used as a basis for cDNA cloning strategies and
for generation of site-specific receptor antibodies. While this
structural motif also carries predictions for receptor function and
regulation, because of the growth factor activity and unusual biphasic
dose-response curve of CCK, new regulatory themes may exist as well.
Novel analogues of CCK exist, which will be used to dissect the
intracellular events involved in these processes, and to help test a new
model for the function and regulation of this receptor. This model
predicts the sequential existence of two affinity states of one receptor
molecule, two independently initiated intracellular activation cascades,
and the presence and sites of regulation of this receptor. This model
predicts the sequential existence of two affinity states of one receptor
molecule, two independently initiated intracellular activation cascades,
and the presence and sites of regulation of a CCK receptor kinase and
phosphatase. Focus will be directed toward the molecular basis of
receptor affinity state, the role of G-p-association in biological
responses, and mechanisms of receptor desensitization, including
uncoupling, sequestration, and down-regulation. This should establish
a paradigm for future investigation of other types of CCK/gastrin
receptors, and to thereby gain insights into the molecular basis of
ligand-receptor interaction and cell activation.
StatusFinished
Effective start/end date8/1/833/31/16

Funding

  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health: $472,003.00
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health: $427,951.00
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health: $490,426.00
  • National Institutes of Health
  • National Institutes of Health: $545,758.00
  • National Institutes of Health
  • National Institutes of Health: $484,490.00
  • National Institutes of Health
  • National Institutes of Health: $440,790.00
  • National Institutes of Health
  • National Institutes of Health: $538,729.00
  • National Institutes of Health: $472,363.00
  • National Institutes of Health: $358,637.00
  • National Institutes of Health
  • National Institutes of Health: $454,015.00
  • National Institutes of Health: $538,729.00
  • National Institutes of Health: $469,984.00
  • National Institutes of Health: $403,384.00
  • National Institutes of Health: $114,066.00
  • National Institutes of Health: $519,872.00
  • National Institutes of Health: $301,421.00

Fingerprint

Cholecystokinin A Receptor
Cholecystokinin Receptors
Cholecystokinin
Ligands
Gallbladder Emptying
Guanine Nucleotides
Organized Financing
Gastrointestinal Hormones
Mutagenesis
Peptides
Phosphorylation
Carrier Proteins
Peptide Receptors
Fluorescence
Energy Transfer
Molecular Structure
Acinar Cells
Health
Gallbladder
Membrane Proteins

ASJC

  • Medicine(all)