scholarly journals Identification of a Novel Family of Targets of PYK2 Related to Drosophila Retinal Degeneration B (rdgB) Protein

1999 ◽  
Vol 19 (3) ◽  
pp. 2278-2288 ◽  
Author(s):  
Sima Lev ◽  
John Hernandez ◽  
Ricardo Martinez ◽  
Alon Chen ◽  
Greg Plowman ◽  
...  
Keyword(s):  
Intracellular Calcium ◽  
Retinal Degeneration ◽  
G Protein ◽  
Binding Proteins ◽  
G Protein Coupled Receptors ◽  
Sequence Motif ◽  
Phosphoinositide Metabolism ◽  
Amino Terminal ◽  
Terminal Domain ◽  
G Protein Coupled

ABSTRACT The protein tyrosine kinase PYK2 has been implicated in signaling pathways activated by G-protein-coupled receptors, intracellular calcium, and stress signals. Here we describe the molecular cloning and characterization of a novel family of PYK2-binding proteins designated Nirs (PYK2 N-terminal domain-interacting receptors). The three Nir proteins (Nir1, Nir2, and Nir3) bind to the amino-terminal domain of PYK2 via a conserved sequence motif located in the carboxy terminus. The primary structures of Nirs reveal six putative transmembrane domains, a region homologous to phosphatidylinositol (PI) transfer protein, and an acidic domain. The Nir proteins are the human homologues of the Drosophila retinal degeneration B protein (rdgB), a protein implicated in the visual transduction pathway in flies. We demonstrate that Nirs are calcium-binding proteins that exhibit PI transfer activity in vivo. Activation of PYK2 by agents that elevate intracellular calcium or by phorbol ester induce tyrosine phosphorylation of Nirs. Moreover, PYK2 and Nirs exhibit similar expression patterns in several regions of the brain and retina. In addition, PYK2-Nir complexes are detected in lysates prepared from cultured cells or from brain tissues. Finally, the Nir1-encoding gene is located at human chromosome 17p13.1, in proximity to a locus responsible for several human retinal diseases. We propose that the Nir and rdgB proteins represent a new family of evolutionarily conserved PYK2-binding proteins that play a role in the control of calcium and phosphoinositide metabolism downstream of G-protein-coupled receptors.

scholarly journals Molecular Basis of Secretin Docking to Its Intact Receptor Using Multiple Photolabile Probes Distributed throughout the Pharmacophore

2011 ◽  
Vol 286 (27) ◽  
pp. 23888-23899 ◽  
Author(s):  
Maoqing Dong ◽  
Polo C.-H. Lam ◽  
Delia I. Pinon ◽  
Keiko Hosohata ◽  
Andrew Orry ◽  
...  
Keyword(s):  
G Protein ◽  
Molecular Basis ◽  
Peptide Mapping ◽  
G Protein Coupled Receptors ◽  
Peptide Ligands ◽  
Amino Terminus ◽  
Amino Terminal ◽  
Binding Cleft ◽  
Mutant Receptors ◽  
G Protein Coupled

The molecular basis of ligand binding and activation of family B G protein-coupled receptors is not yet clear due to the lack of insight into the structure of intact receptors. Although NMR and crystal structures of amino-terminal domains of several family members support consistency in general structural motifs that include a peptide-binding cleft, there are variations in the details of docking of the carboxyl terminus of peptide ligands within this cleft, and there is no information about siting of the amino terminus of these peptides. There are also no empirical data to orient the receptor amino terminus relative to the core helical bundle domain. Here, we prepared a series of five new probes, incorporating photolabile moieties into positions 2, 15, 20, 24, and 25 of full agonist secretin analogues. Each bound specifically to the receptor and covalently labeled single distinct receptor residues. Peptide mapping of labeled wild-type and mutant receptors identified that the position 15, 20, and 25 probes labeled residues within the distal amino terminus of the receptor, whereas the position 24 probe labeled the amino terminus adjacent to TM1. Of note, the position 2 probe labeled a residue within the first extracellular loop of the receptor, a region not previously labeled, providing an important new constraint for docking the amino-terminal region of secretin to its receptor core. These additional experimentally derived constraints help to refine our understanding of the structure of the secretin-intact receptor complex and provide new insights into understanding the molecular mechanism for activation of family B G protein-coupled receptors.

scholarly journals Lysophosphatidylcholine Containing Anisic Acid Is Able to Stimulate Insulin Secretion Targeting G Protein Coupled Receptors

Nutrients ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 1173 ◽  
Author(s):  
Anna Drzazga ◽  
Marta Okulus ◽  
Magdalena Rychlicka ◽  
Łukasz Biegała ◽  
Anna Gliszczyńska ◽  
...  
Keyword(s):  
Diabetes Mellitus ◽  
Insulin Secretion ◽  
Intracellular Calcium ◽  
G Protein ◽  
Phenolic Acids ◽  
G Protein Coupled Receptors ◽  
Calcium Flux ◽  
Pancreatic Cell ◽  
Anisic Acid ◽  
G Protein Coupled

Diabetes mellitus is a worldwide health problem with high rates of mortality and morbidity. Management of diabetes mellitus by dietary components is achievable especially at the initial stage of the disease. Several studies confirmed the antidiabetic activities of simple phenolic acids and lysophosphatidylcholine (LPC). The main goal of this study was to identify new potential insulin secretion modulators obtained by combining the structures of two natural compounds, namely O-methyl derivatives of phenolic acids and phospholipids. LPC and phosphatidylcholine bearing methoxylated aromatic carboxylic acids were tested as potential agents able to improve glucose-stimulated insulin secretion (GSIS) and intracellular calcium mobilization in MIN6 β pancreatic cell line. Our results show that LPC with covalently bonded molecule of p-anisic acid at the sn-1 position was able to induce GSIS and intracellular calcium flux. Notably, 1-anisoyl-2-hydroxy-sn-glycero-3-phosphocholine did not affect the viability of MIN6 cells, suggesting its potential safe use. Furthermore, we have shown that three G protein coupled receptors, namely GPR40, GPR55, and GPR119, are targeted by this LPC derivative.

A Conserved Gβ Binding (GBB) Sequence Motif in Ste20p/PAK Family Protein Kinases

2000 ◽  
Vol 381 (5-6) ◽  
pp. 427-431 ◽  
Author(s):  
E. Leberer ◽  
D. Dignard ◽  
D.Y. Thomas ◽  
T. Leeuw
Keyword(s):  
Map Kinase ◽  
Binding Site ◽  
Protein Kinases ◽  
G Protein ◽  
G Protein Coupled Receptors ◽  
Binding Motif ◽  
Sequence Motif ◽  
Heterotrimeric G Protein ◽  
Family Protein ◽  
G Protein Coupled

Abstract Serine/threonine protein kinases of the Ste20p/PAK family are highly conserved from yeast to man. These protein kinases have been implicated in the signaling from heterotrimeric G proteins to mitogen-activated protein (MAP) kinase cascades and to cytoskeletal components such as myosin-I. In the yeast Saccharomyces cerevisiae, Ste20p is involved in transmitting the mating-pheromone signal from the βγ-subunits of a heterotrimeric G protein to a downstream MAP kinase cascade. We have previously shown that binding of the G-protein β-subunit (Gβ) to a short binding site in the non-catalytic carboxy-terminal region of Ste20p is essential for transmitting the pheromone signal. In this study, we searched protein sequence databases for sequences that are similar to the Gβ binding site in Ste20p. We identified a sequence motif with the consensus sequence S S L ϕP L I/V x ϕϕβ (x: any residue; ϕ: A, I, L, S, or T; β: basic residues) that is solely present in members of Ste20p/PAK family protein kinases. We propose that this sequence motif, which we have designated GBB (G̱β̱ ḇinding) motif, is specifically responsible for binding of Gβ to Ste20p/PAK protein kinases in response to activation of heterotrimeric G protein coupled receptors. Thus, the GBB motif is a novel type of signaling domain that serves to link protein kinases of the Ste20p/PAK family to G protein coupled receptors.

Functional Screening of G Protein–Coupled Receptors by Measuring Intracellular Calcium with a Fluorescence Microplate Reader

2002 ◽  
Vol 7 (3) ◽  
pp. 233-246 ◽  
Author(s):  
Matthias U. Kassack ◽  
Barbara Höfgen ◽  
Jochen Lehmann ◽  
Niels Eckstein ◽  
J. Mark Quillan ◽  
...  
Keyword(s):  
Intracellular Calcium ◽  
G Protein ◽  
G Protein Coupled Receptors ◽  
Functional Screening ◽  
Microplate Reader ◽  
G Protein Coupled
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