Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01350 (gastrin)
 9,683 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A major concern associated with the use of recombinant adenoviral vectors is that viral receptors are found on the surface of many cell types and systemic in vivo delivery of the viral vector could result in uncontrolled and widespread expression of therapeutic molecules in many tissues. To construct a cell-type specific recombinant adenoviral vector, a new binding specificity must be added to the virus, and the endogenous binding specificity of the virus must be ablated. In order to introduce a new binding specificity to recombinant adenoviral vectors, the coding sequence of a physiological ligand, the terminal decapeptide of the gastrin releasing peptide (GRP), was placed at the 3' end of the coding sequence of the adenovirus type 5 fiber gene. The resulting fiber-GRP fusion protein was expressed using a T7 vaccinia expression system and has been shown to assemble protein trimers whose quaternary structure is indistinguishable from that of wild-type protein. The fiber-GRP fusion protein was correctly transported to the nucleus of HeLa cells immediately after synthesis. The added GRP ligand in the fiber-GRP fusion protein was accessible to binding by an anti-GRP antibody in both the monomeric and trimeric forms of the chimeric protein. These studies suggest that new cell type specificities for adenovirus binding might be introduced by genetic fusion of peptide ligands on to the carboxyl terminus of the adenovirus fiber protein.
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PMID:Addition of a short peptide ligand to the adenovirus fiber protein. 854 56

Gastrin releasing peptide (GRP) regulates critical gastrointestinal functions via the GRP receptor (GRPR). GRPR internalization and recycling have been proposed to play an important role in the cellular response to GRP. Our aim was to develop a direct method for investigating GRPR trafficking in living cells. A chimeric protein, consisting of GRPR fused to green fluorescent protein (GFP), was expressed in epithelial cells. Ligand and receptor interactions were examined with radiolabeled agonist and fluorescent imaging. In comparison with epithelial cells expressing wild-type GRPR, the GRPR-GFP expressing cells showed similar ligand binding affinity, GRP-stimulated Ca2+ signaling, and GRP-initiated internalization. In GRPR-GFP expressing cells treated with fluorescently labeled ligand, receptor and ligand trafficking was directly visualized. Upon ligand binding, the receptor-ligand complex coalesced into vesicles prior to internalization and migration to the perinuclear space. Whereas a portion of the receptors were observed to return to the plasma membrane, the ligand remained in the perinuclear space. Hyperosmolar solution prevented ligand and receptor internalization, and bafilomycin inhibited receptor recycling. We demonstrate that GRPR-GFP is physiologically similar to wild-type GRPR, and permits direct visualization of intracellular trafficking processes in individual living cells with minimal toxicity over several hours.
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PMID:Visualization of internalization and recycling of the gastrin releasing peptide receptor-green fluorescent protein chimera expressed in epithelial cells. 1010 Mar 28

Control of enzymatic function by peptide hormones can occur at a number of different levels and can involve diverse pathways that regulate cleavage, intracellular trafficking, and protein degradation. Gastrin is a peptide hormone that binds to the cholecystokinin B-gastrin receptor and regulates the activity of L-histidine decarboxylase (HDC), the enzyme that produces histamine. Here we show that gastrin can increase the steady-state levels of at least six HDC isoforms without affecting HDC mRNA levels. Pulse-chase experiments indicated that HDC isoforms are rapidly degraded and that gastrin-dependent increases are due to enhanced isoform stability. Deletion analysis identified two PEST domains (PEST1 and PEST2) and an intracellular targeting domain (ER2) which regulate HDC protein expression levels. Experiments with PEST domain fusion proteins demonstrated that PEST1 and PEST2 are strong and portable degradation-promoting elements which are positively regulated by both gastrin stimulation and proteasome inhibition. A chimeric protein containing the PEST domain of ornithine decarboxylase was similarly affected, indicating that gastrin can regulate the stability of other PEST domain-containing proteins and does so independently of antizyme/antizyme inhibitor regulation. At the same time, endoplasmic reticulum localization of a fluorescent chimera containing the ER2 domain of HDC was unaltered by gastrin stimulation. We conclude that gastrin stabilization of HDC isoforms is dependent upon two transferable and sequentially unrelated PEST domains that regulate degradation. These experiments revealed a novel regulatory mechanism by which a peptide hormone such as gastrin can disrupt the degradation function of multiple PEST-domain-containing proteins.
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PMID:Amino- and carboxy-terminal PEST domains mediate gastrin stabilization of rat L-histidine decarboxylase isoforms. 1084 18