Combining with a peptide and transmitting the signal across the membrane by activating an associated G-protein; promotes the exchange of GDP for GTP on the alpha subunit of a heterotrimeric G-protein complex.
Combining with an extracellular or intracellular signal and transmitting the signal from one side of the membrane to the other to initiate a change in cell activity.
A complementary DNA for a glucagon-like peptide-1 receptor was isolated from a human pancreatic islet cDNA library. The isolated clone encoded a protein with 90% identity to the rat receptor. In stably transfected fibroblasts, the receptor bound [125I]GLP-1 with high affinity (Kd = 0.5 nM) and was coupled to adenylate cyclase as detected by a GLP-1-dependent increase in cAMP production (EC50 = 93 pM). Two peptides from the venom of the lizard Heloderma suspectum, exendin-4 and exendin-(9-39), displayed similar ligand binding affinities to the human GLP-1 receptor. Whereas exendin-4 acted as an agonist of the receptor, inducing cAMP formation, exendin-(9-39) was an antagonist of the receptor, inhibiting GLP-1-induced cAMP production. Because GLP-1 has been proposed as a potential agent for treatment of NIDDM, our present data will contribute to the characterization of the receptor binding site and the development of new agonists of this receptor.
A complementary DNA for a glucagon-like peptide-1 receptor was isolated from a human pancreatic islet cDNA library. The isolated clone encoded a protein with 90% identity to the rat receptor. In stably transfected fibroblasts, the receptor bound [125I]GLP-1 with high affinity (Kd = 0.5 nM) and was coupled to adenylate cyclase as detected by a GLP-1-dependent increase in cAMP production (EC50 = 93 pM). Two peptides from the venom of the lizard Heloderma suspectum, exendin-4 and exendin-(9-39), displayed similar ligand binding affinities to the human GLP-1 receptor. Whereas exendin-4 acted as an agonist of the receptor, inducing cAMP formation, exendin-(9-39) was an antagonist of the receptor, inhibiting GLP-1-induced cAMP production. Because GLP-1 has been proposed as a potential agent for treatment of NIDDM, our present data will contribute to the characterization of the receptor binding site and the development of new agonists of this receptor.
Any intracellular signal transduction in which the signal is passed on within the cell via cyclic AMP (cAMP). Includes production of cAMP, and downstream effectors that further transmit the signal within the cell.
The actions of glucagon-like peptide-1(7-36)amide (GLP-1(7-36)amide) on cellular signalling were studied in human embryonal kidney 293 (HEK 293) cells stably transfected with the cloned human GLP-1 receptor. The cloned GLP-1 receptor showed a single high-affinity binding site (Kd = 0.76 nM). Binding of GLP-1(7-36)amide stimulated cAMP production in a dose-dependent manner (EC50 = 0.015 nM) and caused an increase in the intracellular free Ca2+ concentration ([Ca2+]i). The latter effect reflected Ca(2+)-induced Ca2+ release and was suppressed by ryanodine. We propose that the ability of GLP-1(7-36)amide to increase [Ca2+]i results from sensitization of the ryanodine receptors by a protein kinase A dependent mechanism.
The actions of glucagon-like peptide-1(7-36)amide (GLP-1(7-36)amide) on cellular signalling were studied in human embryonal kidney 293 (HEK 293) cells stably transfected with the cloned human GLP-1 receptor. The cloned GLP-1 receptor showed a single high-affinity binding site (Kd = 0.76 nM). Binding of GLP-1(7-36)amide stimulated cAMP production in a dose-dependent manner (EC50 = 0.015 nM) and caused an increase in the intracellular free Ca2+ concentration ([Ca2+]i). The latter effect reflected Ca(2+)-induced Ca2+ release and was suppressed by ryanodine. We propose that the ability of GLP-1(7-36)amide to increase [Ca2+]i results from sensitization of the ryanodine receptors by a protein kinase A dependent mechanism.
Receptors which transduce extracellular signals across the cell membrane. At the external side they receive a ligand (a photon in case of opsins), and at the cytosolic side they activate a guanine nucleotide-binding (G) protein. These receptors are hydrophobic proteins that cross the membrane seven times.
A reference proteome is a set of protein sequences derived from a complete proteome which constitutes a defined standard for a particular user community. Reference proteomes are manually defined according to a number of criteria. They cover the proteomes of well- studied model organisms and other proteomes of interest for biomedical and biotechnological research. Reference proteomes have been selected to provide broad coverage of the tree of life, and constitute a representative cross-section of the taxonomic diversity to be found within UniProtKB.