The N-terminal coiled-coil domain of beta is essential for gamma association: a model for G-protein beta gamma subunit interaction.

Garritsen, Anja; Galen, P. J. M. van; Simonds, William F.

doi:10.1073/pnas.90.16.7706

Cited by 61 publications

(53 citation statements)

References 38 publications

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“…Some WD-40 proteins, like RACK1, are made up entirely of WDrepeats IRon et al 1994). Others, including AN11, contain amino-terminal and carboxy-terminal extensions of various lengths, which may contribute to the regulatory function, as shown for the Gq3 subunit and the phospholipase A2 activating protein (Clark et al 1991;Garritsen et al 1993). Apart from the relatively loose WD-repeat consensus sequence, no significant sequence homology has been found between AN11 and any other identified WD-repeat protein, indicating that AN11 is a new member of this rapidly expanding family of proteins.…”

Section: Discussionmentioning

confidence: 98%

The an11 locus controlling flower pigmentation in petunia encodes a novel WD-repeat protein conserved in yeast, plants, and animals.

Vetten¹,

Quattrocchio²,

Mol³

et al. 1997

Genes Dev.

358

304

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In petunia flowers, the loci anl, an2, and anll control the pigmentation of the flower by stimulating the transcription of anthocyanin biosynthetic genes. The anl and an2 locus were recently cloned and encode a basic helix-loop-helix (bHLH) and MYB-domain transcriptional activator, respectively. Here, we report the isolation of the anll locus by transposon tagging. RNA gel blot experiments show that anll is expressed independently from anl and an2 throughout plant development, as well as in tissues that do not express the anthocyanin pathway. It encodes a novel WD-repeat protein that is highly conserved even in species that do not produce anthocyanins such as yeast, nematodes, and mammals. The observation that the human anll homolog partially complements the anll petunia mutant in transient assays shows that sequence similarity reflects functional conservation. Overexpression of an2 in anll-petals restored the activity of a structural anthocyanin gene in transient assays, indicating that AN11 acts upstream of AN2. Cell fractionation experiments show that the bulk of the ANll protein is localized in the cytoplasm. Taken together, this indicates that ANll is a cytoplasmic component of a conserved signal transduction cascade that modulates AN2 function in petunia, thereby linking cellular signals with transcriptional activation.

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Section: Discussionmentioning

confidence: 98%

The an11 locus controlling flower pigmentation in petunia encodes a novel WD-repeat protein conserved in yeast, plants, and animals.

Vetten¹,

Quattrocchio²,

Mol³

et al. 1997

Genes Dev.

358

304

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“…1D demonstrates that both chimeras are capable of activating PI-PLC-f32 very well when expressed with y2. To address the possibility that the chimeras can interact with yl but cannot activate PI-PLC-f32, we tested for the direct interaction of the chimeras with yl by measuring the translocation of Gf3 subunits from the membrane fraction to the cytosol, based on the finding that in transfected cells, ylC71L, a Gyl that cannot be isoprenylated, will shift GP3 subunits that it can dimerize with from the membrane fraction to the cytosol (28,35). Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Computer-assisted molecular modeling of the j3 and y subunits revealed that their N-terminal regions can form a-helical coiled-coil structures and it was postulated that 13 and y dimerize through these regions (34,35). However, the N-terminal coiled-coil structure cannot account, by itself, for the exceptional stability of f3y dimers (36).…”

mentioning

confidence: 99%

A segment of the C-terminal half of the G-protein beta 1 subunit specifies its interaction with the gamma 1 subunit.

Katz

1995

Proc. Natl. Acad. Sci. U.S.A.

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The f3 and y subunits of the heterotrimeric guanine nucleotide binding (G protein) act as a dimer and directly regulate various signal transduction pathways. By using cotransfection assays, we tested the ability of several fty combinations to activate inositol phospholipid-specific phospholipase C (PI-PLC)-j82. Our findings indicate that only ,8ry combinations that form dimers will activate PI-PLC-182. Since Gj81 interacts with Gyl, while Gj82 cannot, chimeras between G181 and G182 were used to identify the regions in i31 that determine its specific association with yl. Our evidence demonstrates that a chimera between j82 and 131 that contains the C-terminal 173 amino acids of 131 can interact and activate PI-PLC-f32 with yl. Chimeras that contain portions of the f31 C-terminal region display a weaker association with yl. Furthermore, the contribution of each of these regions depends on the sequence context of each chimeric protein. However, the segment between residues 210 and 293 of 81 consistently plays a critical role in specifying association with 'yl.Heterotrimeric guanine nucleotide binding proteins (G proteins) transduce signals from cell surface receptors to a variety of effector systems via a guanine nucleotide binding and hydrolysis cycle. The Ga subunits activate second messengergenerating systems (1-3). Furthermore, there is evidence that f3y dimers also have an active role in signal transduction pathways (4-6). Recent efforts have shown that the Goy dimer can contribute to the selective coupling of the heterotrimeric G protein to its receptor (7-9) and can regulate various downstream effector systems such as adenylyl cyclase, inositol phospholipid-specific phospholipase C (PI-PLC), the atrial potassium channel, a cytosolic inositol phospholipid 3 kinase, and mitogen-activated protein kinases (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20). In addition, G13y can facilitate the translocation of specific kinases to the membrane (21,22).At present, five distinct 13 subunits have been cloned (23-25), and there are at least seven different G-y subunits (23,24,26). Testing for the interaction between 13 and y subunits by using cell-free and transfection systems has indicated that the (31 subunit can interact with both yl and y2 subunits, whereas (32 can interact with y2 and not with yl (27,28). By using purified recombinant 13y dimers, 131 has been found to dimerize with yl, 'y2, y3, yS, and y7, whereas (32 can dimerize with y2, 'y3, y5, and 'y7 but not with yl (29-31). Similar findings came from transfection studies testing the ability of 13,y combinations consisting of 131 or 12 with yl, y2, or 'yS to activate PI-PLC-,B2 (11, 32). The structural basis for the interactions between the 1 and -y subunits has not been established.Crosslinking experiments show that yl can interact with the N terminus of 31 (33). Computer-assisted molecular modeling of the j3 and y subunits revealed that their N-terminal regions can form a-helical coiled-coil structures and it was postulated that 13 and y dimerize throu...

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“…This question might be answered by understanding the proposed roles of Gg-or Gb-subunits in G-protein signaling. In general, G-protein g-subunits are found to play the following roles: (1) transducing signals by forming a heterodimer with Gb (Whiteway et al 1989;Garritsen et al 1993), (2) promoting G-protein activation by binding and modulating efficiency of receptor-G-protein coupling (Lambright et al 1994;Yasudaet al 1996;Rondard et al 2001;Chinault and Blumer 2003), (3) granting selective and discrete coupling of GPCRs with Gb (Kisselev et al 1995(Kisselev et al , 1999, and (4) promoting activation of the Gbg-effectors that cocluster with receptors (Chinault and Blumer 2003). Similarly, Gb-subunits were found to play an important role in providing a GPCR binding site for the G protein, which is critical for G-protein activation (Taylor et al Figure 6.-Deletion of gpgA cannot bypass the need for fluG in conidiation.…”

Section: Discussionmentioning

confidence: 99%

Multiple Roles of a Heterotrimeric G-Protein γ-Subunit in Governing Growth and Development of Aspergillus nidulans

Seo¹,

Han²,

2005

Genetics

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Vegetative growth signaling in the filamentous fungus Aspergillus nidulans is primarily mediated by the heterotrimeric G-protein composed of FadA (Ga), SfaD (Gb), and a presumed Gg. Analysis of the A. nidulans genome identified a single gene named gpgA encoding a putative Gg-subunit. The predicted GpgA protein consists of 90 amino acids showing 72% similarity with yeast Ste18p. Deletion (D) of gpgA resulted in restricted vegetative growth and lowered asexual sporulation. Moreover, similar to the DsfaD mutant, the DgpgA mutant was unable to produce sexual fruiting bodies (cleistothecia) in self-fertilization and was severely impaired with cleistothecial development in outcross, indicating that both SfaD and GpgA are required for fruiting body formation. Developmental and morphological defects caused by deletion of flbA encoding an RGS protein negatively controlling FadA-mediated vegetative growth signaling were suppressed by DgpgA, indicating that GpgA functions in FadA-SfaD-mediated vegetative growth signaling. However, deletion of gpgA could not bypass the need for the early developmental activator FluG in asexual sporulation, suggesting that GpgA functions in a separate signaling pathway. We propose that GpgA is the only A. nidulans Gg-subunit and is required for normal vegetative growth as well as proper asexual and sexual developmental progression.

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The N-terminal coiled-coil domain of beta is essential for gamma association: a model for G-protein beta gamma subunit interaction.

Cited by 61 publications

References 38 publications

The an11 locus controlling flower pigmentation in petunia encodes a novel WD-repeat protein conserved in yeast, plants, and animals.

The an11 locus controlling flower pigmentation in petunia encodes a novel WD-repeat protein conserved in yeast, plants, and animals.

A segment of the C-terminal half of the G-protein beta 1 subunit specifies its interaction with the gamma 1 subunit.

Multiple Roles of a Heterotrimeric G-Protein γ-Subunit in Governing Growth and Development of Aspergillus nidulans

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