Deactivation of visual transduction without guanosine triphosphate hydrolysis by G protein

Science ◽  
1992 ◽  
Vol 257 (5074) ◽  
pp. 1255-1258 ◽  
Author(s):  
M. Erickson ◽  
P Robinson ◽  
J Lisman
Keyword(s):  
G Protein ◽  
Guanosine Triphosphate ◽  
Visual Transduction

scholarly journals Epidermal growth factor-induced phosphoinositide hydrolysis in permeabilized 3T3 cells: lack of guanosine triphosphate dependence and inhibition by tyrosine-containing peptides.

1990 ◽  
Vol 1 (9) ◽  
pp. 615-620 ◽  
Author(s):  
G F Verheijden ◽  
I Verlaan ◽  
J Schlessinger ◽  
W H Moolenaar
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
G Protein ◽  
Egf Receptor ◽  
Phosphoinositide Hydrolysis ◽  
3T3 Cells ◽  
Guanosine Triphosphate ◽  
Intact Cells ◽  
Epidermal Growth ◽  
Gamma S

The possible involvement of a stimulatory guanosine triphosphate (GTP)-binding (G) protein in epidermal growth factor (EGF)-induced phosphoinositide hydrolysis has been investigated in permeabilized NIH-3T3 cells expressing the human EGF receptor. The mitogenic phospholipid lysophosphatidate (LPA), a potent inducer of phosphoinositide hydrolysis, was used as a control stimulus. In intact cells, pertussis toxin partially inhibits the LPA-induced formation of inositol phosphates, but has no effect on the response to EGF. In cells permeabilized with streptolysin-O, guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) dramatically increases the initial rate of inositol phosphate formation induced by LPA. In contrast, activation of phospholipase C (PLC) by EGF occurs in a GTP-independent manner. Guanine 5'-O-(2-thiodiphosphate) (GDP beta S) which keeps G proteins in their inactive state, blocks the stimulation by LPA and GTP gamma S, but fails to affect the EGF-induced response. Tyrosine-containing substrate peptides, when added to permeabilized cells, inhibit EGF-induced phosphoinositide hydrolysis without interfering with the response to LPA and GTP gamma S. These data suggest that the EGF receptor does not utilize an intermediary G protein to activate PLC and that receptor-mediated activation of effector systems can be inhibited by exogenous substrate peptides.

scholarly journals Effects of carboxyl methylation of photoreceptor G protein gamma-subunit in visual transduction.

1994 ◽  
Vol 269 (7) ◽  
pp. 5163-5170
Author(s):  
Y. Fukada ◽  
T. Matsuda ◽  
K. Kokame ◽  
T. Takao ◽  
Y. Shimonishi ◽  
...  
Keyword(s):  
G Protein ◽  
Visual Transduction ◽  
Gamma Subunit ◽  
Carboxyl Methylation

scholarly journals 3.6.5.2 Small monomeric GTPases (version 2019.4) in the IUPHAR/BPS Guide to Pharmacology Database

2019 ◽  
Vol 2019 (4) ◽  
Author(s):  
Elena Faccenda
Keyword(s):  
G Protein ◽  
G Proteins ◽  
Small Gtpase ◽  
Alpha Subunit ◽  
Heterotrimeric G Proteins ◽  
Guanosine Triphosphate ◽  
Guanosine Diphosphate ◽  
Ras Gtpases ◽  
Small G Proteins

Small G-proteins, are a family of hydrolase enzymes that can bind and hydrolyze guanosine triphosphate (GTP). They are a type of G-protein found in the cytosol that are homologous to the alpha subunit of heterotrimeric G-proteins, but unlike the alpha subunit of G proteins, a small GTPase can function independently as a hydrolase enzyme to bind to and hydrolyze a guanosine triphosphate (GTP) to form guanosine diphosphate (GDP). The best-known members are the Ras GTPases and hence they are sometimes called Ras subfamily GTPases.

The structure of bacteriorhodopsin and its relevance to the visual opsins and other seven-helix G-protein coupled receptors

1990 ◽  
Vol 326 (1236) ◽  
pp. 379-389 ◽  
Keyword(s):  
G Protein ◽  
Chloride Ion ◽  
G Protein Coupled Receptors ◽  
Three Dimensions ◽  
Ion Pump ◽  
Direct Sequence ◽  
Transmembrane Helices ◽  
Visual Transduction ◽  
Receptor Proteins ◽  
G Protein Coupled

Bacteriorhodopsin is a light-driven hydrogen-ion pump whose structure is known to about 6.0 Å in three dimensions and 2.8 Å in projection. It consists of seven transmembrane helices surrounding the chromophore, retinal. Halorhodopsin is a second member of the same family of membrane proteins, both of them from the cell membrane of halobacteria. Halorhodopsin is a light-driven chloride-ion pump but has very close homology to bacteriorhodopsin, especially around the retinal. In contrast, the visual opsins that are responsible for the primary step in visual transduction in all eukaryotes from Drosophila upwards, form a separate family with no direct sequence homology to the bacteriorhodopsin family. The visual opsin family now includes about 15 other receptor proteins, all of which activate G-protein cascades, including the β-adrenergic receptor as well as several others. Despite the lack of clear relations at the level of amino acid sequence, there are topographical similarities between the bacteriorhodopsin and the visual opsin families in the nature and site of chromophore attachment, the number of transmembrane helices and the positions of the amino and carboxyl termini in the membrane. These suggest that if the two were at one time closely related, they have diverged too far to have sequences that are detectably similar.

scholarly journals The small G-protein MglA connects to the MreB actin cytoskeleton at bacterial focal adhesions

2015 ◽  
Vol 210 (2) ◽  
pp. 243-256 ◽  
Author(s):  
Anke Treuner-Lange ◽  
Eric Macia ◽  
Mathilde Guzzo ◽  
Edina Hot ◽  
Laura M. Faure ◽  
...  
Keyword(s):  
Actin Cytoskeleton ◽  
G Protein ◽  
Myxococcus Xanthus ◽  
Focal Adhesions ◽  
Gliding Motility ◽  
Guanosine Triphosphate ◽  
Cell Pole ◽  
Peptidoglycan Synthesis ◽  
Small G Protein ◽  
Guanosine Triphosphatase

In Myxococcus xanthus the gliding motility machinery is assembled at the leading cell pole to form focal adhesions, translocated rearward to propel the cell, and disassembled at the lagging pole. We show that MglA, a Ras-like small G-protein, is an integral part of this machinery. In this function, MglA stimulates the assembly of the motility complex by directly connecting it to the MreB actin cytoskeleton. Because the nucleotide state of MglA is regulated spatially and MglA only binds MreB in the guanosine triphosphate–bound form, the motility complexes are assembled at the leading pole and dispersed at the lagging pole where the guanosine triphosphatase activating protein MglB disrupts the MglA–MreB interaction. Thus, MglA acts as a nucleotide-dependent molecular switch to regulate the motility machinery spatially. The function of MreB in motility is independent of its function in peptidoglycan synthesis, representing a coopted function. Our findings highlight a new function for the MreB cytoskeleton and suggest that G-protein–cytoskeleton interactions are a universally conserved feature.

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