Rhodopsin and the retinal G-protein distinguish among G-protein beta gamma subunit forms

Fawzi, Ahmad; Fay, David S.; Murphy, E. Angela; Tamir, Haya; Erdos, Joseph; Northup, John K.

doi:10.1016/s0021-9258(18)98880-0

Cited by 82 publications

(10 citation statements)

References 57 publications

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“…The interaction of a-gustducin with rhodopsin (Figure 4) was measured only in the absence of fly-heterodimers and was compared with equivalent measurements of a-transducin. It has been shown that 8y-heterodimers reduce the concentration of rhodopsin needed to activate a-transducin [18] and that various /Jy-heterodimers differ in their efficacy [15]. However, at saturating rhodopsin concentration, the extent of GTP[yS] binding is approximately equal for heterotrimeric transducin and atransducin.…”

Section: Discussionmentioning

confidence: 99%

“…The [y-35S]GTP[yS]-binding assay was based on that described previously [15]. Rhodopsin-catalysed GTP[yS]-binding to atransducin or a-gustducin was carried out in a 10 1l assay volume in 20 mM MOPS (pH 7.5), 3 mM MgSO4, 1 mM EDTA, 3 mg/ml BSA, 1 mM dithiothreitol (DTT), 3.6 mM CHAPS and 0.1 juM [y-35S]GTP [yS].…”

Section: Construction Of Recombinant Baculoviral A-gustducinmentioning

confidence: 99%

“…Pertussis toxin-catalysed ADP-ribosylation Pertussis toxin-catalysed ADP-ribosylation -of SJ9 cell extracts, purified a-gustducin and a-transducin was examined under a number of conditions [15]. The extent of modification of soluble cell extracts (20 dul) and purified G-protein (5 nM) was de-termined with and without addition of either bovine brain or retinal fly-dimers (0.3 ,uM).…”

Section: Activation Of Cgmp-pdementioning

confidence: 99%

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Functional expression of the taste specific G-protein, α-gustducin

Hoon

Northup

Margolskee

et al. 1995

Biochemical Journal

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The taste-specific G-protein alpha-subunit, alpha-gustducin, was expressed using a baculovirus based system. alpha-Gustducin was demonstrated to be myristoylated and was also palmitoylated in insect larval cells. Recombinant alpha-gustducin was purified to homogeneity. Neither receptors nor effectors that interact with gustducin in taste are known. However, alpha-gustducin has a close structural similarity to the visual G-protein, alpha-transducin. Therefore alpha-gustducin was reconstituted with components of the visual system to determine the degree of its functional similarity with alpha-transducin. Despite the fact that the sequences of alpha-gustducin and alpha-transducin share only 80% identity with each other, the interactions and functions of these two proteins were quantitatively identical. These included the interaction with receptor, bovine rhodopsin, with effector, bovine retinal cyclic GMP-phosphodiesterase, and with bovine brain and retinal G-protein beta gamma-heterodimers; receptor-catalysed GDP-GTP exchange and the intrinsic GTPase activity of alpha-gustducin and alpha-transducin were also identical. Gi alpha which is 70% identical with alpha-transducin interacts with different receptor and effector proteins and has very different guanine-nucleotide binding properties. Therefore, the functional equivalence of alpha-gustducin and alpha-transducin suggest that taste buds are likely to contain receptor and effector proteins that share many properties with their retinal equivalents.

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Section: Discussionmentioning

confidence: 99%

Section: Construction Of Recombinant Baculoviral A-gustducinmentioning

confidence: 99%

Section: Activation Of Cgmp-pdementioning

confidence: 99%

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Functional expression of the taste specific G-protein, α-gustducin

Hoon

Northup

Margolskee

et al. 1995

Biochemical Journal

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“…Anti sen se experiments have shown th at a soma tostatin a nd an m4-muscarinic receptor in a single cell require f3 y subunits compo sed of different, specific 13 a nd Y polypeptides to trigger Go-dependent inhibition of Ca 2 + currents (16,17). f3 y complexes of different compo sition differ in th eir ability to facili tate rhodopsin-catalyzed binding ofGTPyS to at (54)(55)(56). Moreover, a farnesylated peptide mimicking th e C terminus of Yl can directly stabilize metarhodopsin II , th e active form of rhodopsin (57); this shows that st ruct ura lly specific segments of a y subunit can interact directly with a receptor a nd, by implication , help to det ermine receptor-G protein specificity .…”

Section: Discussionmentioning

confidence: 99%

Potentiation of Gi-mediated Phospholipase C Activation by Retinoic Acid in HL-60 Cells

Iiri

Homma

Ohoka

et al. 1995

Journal of Biological Chemistry

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Differentiated HL-60 cells acquire responsiveness to fMet-Leu-Phe (fMLP), which activates phospholipase C and O2- generation in a pertussis toxin-sensitive manner. Addition of retinoic acid (RA) for the last 24 h during dimethyl sulfoxide (Me2SO)-induced differentiation enhanced fMLP-dependent signals and interaction between fMLP receptor and G(i). RA modifies both the function and subunit composition of G(i)2, the predominant G(i) of HL-60 membranes, as shown by comparing purified G(i)2 from membranes of Me2SO-treated cells (D-G(i)2) to G(i)2 from membranes of cells treated with both Me2SO and RA (DR-G(i)2). As compared to D-G(i)2, DR-G(i)2 induced more fMLP binding when added to membranes of pertussis toxin-treated HL-60 cells and, in the presence of GTP gamma S, stimulated beta gamma-sensitive phospholipase C in extracts of HL-60 cells to a much greater extent at a lower concentrations. Immunoblasts revealed that RA induced expression of the gamma 2 subunit, which was otherwise undetectable in G(i)2 purified from HL-60 cells or in HL-60 membranes. Possibly by inducing expression of gamma 2, RA alters two functions of the G(i) beta gamma subunit, modulation of fMLP receptor-G(i)2 coupling and activation of the effector, Phospholipase C.

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“…In principle, different combina tions of P and y could enhance the specificity of an individual G-protein sld either by: (i) filtering receptor inputs; or (ii) by selecting among available effectors. The first possibility, which depends on the fact that receptors recognize and interact with the aPy trimer rather than with Ga (or GPy ) alone, is supported by reasonably strong evidence (Fawzi et al 1991;Kisselev & Gautam, 1993; Kleuss e 199 experiments have shown that certain receptors can activate a specific Ga much more efficiently in the presence of specific Py complexes (Fawzi et al 1991;Kisselev and Gautam, 1993). In an elegant series of antisense experiments in intact cultured cells, Kleuss et al reported (Kleuss et a l .…”

Section: Trimeric G Proteins Are a Signal Linking Devicementioning

confidence: 99%

GTPases: a family of molecular switches and clocks

Bourne

1995

Phil. Trans. R. Soc. Lond. B

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Members of the GTPase superfamily share a core domain with a conserved three-dimensional structure and a common GTPase cycle, but perform a wide variety of regulatory tasks in eukaryotic cells. Evolution has created functional diversity from the conserved GTPase structure in two principal ways: (i) by combining in the product of a single gene the core GTPase domain attached to one or more additional folded domains; (ii) by building around a core GTPase an assembly of proteins encoded by different genes. Analysis of the patterns of conserved amino acid side chains on surfaces of G alpha proteins reveals interfaces with other proteins in the G-protein signal linking device.

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Rhodopsin and the retinal G-protein distinguish among G-protein beta gamma subunit forms

Cited by 82 publications

References 57 publications

Functional expression of the taste specific G-protein, α-gustducin

Functional expression of the taste specific G-protein, α-gustducin

Potentiation of Gi-mediated Phospholipase C Activation by Retinoic Acid in HL-60 Cells

GTPases: a family of molecular switches and clocks

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