G protein diversity is increased by associations with a variety of gamma subunits.

Gautam, N.; Northup, John K.; Tamir, Haya

doi:10.1073/pnas.87.20.7973

Cited by 112 publications

(84 citation statements)

References 32 publications

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“…Its higher level of interaction with ␤1 and ␤2 is thus consistent with the ubiquitous distribution of these two ␤ subunit types. ␥3 is a subunit type that is mainly present in brain and is expressed at very high levels (18). Immunohistochemistry with antibodies specific to this subunit show highly restricted expression of the protein in brain and retina.…”

Section: Discussionmentioning

confidence: 99%

“…This raised the possibility of determining the efficacy of complex formation between different ␤ and ␥ subunit types based on the magnitude of reporter activity. Using this system, we tested interaction between the five ␤ subunit types (␤1-␤5) that have been identified so far and six ␥ subunit types (␥1-␥5 and ␥7) with different primary structures and tissue-specific expression (7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21). The interaction between the ␤ and ␥ subunits is of special interest because these two subunits are tightly bound as a complex and are thought to act inside the cells in this form (2).…”

mentioning

confidence: 99%

“…1 ␥2 is present in several tissues (16). ␥3 and ␥4 are brain-specific (18,21). ␥5 is ubiquitous (19).…”

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confidence: 99%

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Differential Ability to Form the G Protein βγ Complex among Members of the β and γ Subunit Families

Yan

Kalyanaraman

Gautam

1996

Journal of Biological Chemistry

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We have determined the relative abilities of several members of the G protein ␤ and ␥ subunit families to associate with each other using the yeast two-hybrid system. We show first that the mammalian ␤1 and ␥3 fusion proteins form a complex in yeast and that formation of the complex activates the reporter gene for ␤-galactosidase. Second, the magnitude of reporter activity stimulated by various combinations of ␤ and ␥ subunit types varies widely. Third, the reporter activity evoked by a particular combination of ␤ and␥ subunit types is not correlated with the expression levels of these subunit types in the yeast cells. Finally, the reporter activity shows a direct relationship with the amount of hybrid ␤␥ complex formed in the cell as determined by immunoprecipitation. These results suggest that different ␤ and ␥ subunit types interact with each other with widely varying abilities, and this in combination with the level of expression of a subunit type in a mammalian cell determines which G protein will be active in that cell. The strong preference of all ␥ subunit types for the ␤1 subunit type explains the preponderence of this subunit type in most G proteins.Most of the neurohormonal signaling pathways in mammals are mediated by heterotrimeric G proteins (1, 2). Most cells contain many different G protein subunit types, and yet particular agonists evoke a highly specific response in a cell by activating a defined G protein-mediated signaling pathway (3). Various mechanisms can contribute to this specificity. For instance, in a cell that contains many different ␣, ␤, and ␥ subunit types, only certain types may be capable of forming a heterotrimeric complex because of the differences in the intrinsic affinity of these subunit types for one another. It has been shown that interactions between two different ␥ subunit types (␥1 and ␥2) and three different ␤ subunit types (␤1-␤3) are selective, indicating that this is indeed a mechanism for achieving specificity (4, 5). However, these experiments were performed using in vivo or in vitro systems that could detect differences in the ability of these subunit types to interact but were not sufficiently sensitive to detect low level interaction between some of the subunit types. To obtain a more sensitive measure of the interaction between various members of the ␤ and ␥ subunit families, we used the yeast two-hybrid system. In this system, the proteins with the potential to interact are expressed as hybrids of two different domains of a transcription factor. If the proteins interact with each other, the transcription factor domains are in proximity and capable of activating a promoter that controls reporter activity (6). We chose this system because it measures protein-protein interaction in a yeast cell and is therefore a reasonably accurate reflection of the ability of the interacting proteins to form a complex in a cell. Furthermore, it is highly sensitive in comparison with the methods used before to measure protein-protein interaction. For instance, in an assay of in...

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

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Differential Ability to Form the G Protein βγ Complex among Members of the β and γ Subunit Families

Yan

Kalyanaraman

Gautam

1996

Journal of Biological Chemistry

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“…Comparison of the amino acid sequence of the squid G-y with those of previously cloned or sequenced mammalian and insect y-subunits [23,[28][29][30][31] (Fig. 3) reveals some similarity in primary structure between the proteins.…”

Section: Resultsmentioning

confidence: 99%

“…Conservative replacements are shown in upper case, the rest of the sequence in lower case. Dros, Drosophila G-7 [23]; trans, bovine transduein y [28]; gem2, gain3, bovine brain G-Ts [29,30]; BarnS, bovine liver 7 [31].…”

Section: Resultsmentioning

confidence: 99%

The γ‐subunit of the principal G‐protein from squid (Loligo forbesi) photoreceptors contains a novel N‐terminal sequence

et al. 1992

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The squid (Loligo forbesi) visual system presents as accessible a system for study of G‐protein mediated signal transduction as the vertebrate rod outer segment with the added advantage that the major G‐protein is a member of the Gq‐class. Here the cDNA clone encoding the γ‐subunit of this G‐protein is reported, thereby completing the molecular cloning of the heterotrimeric G‐protein. The deduced protein structure of G‐γ has relatively little sequence identity with known mammalian counterparts particularly in comparison with the relatively high degree found for both the α‐ and β‐subunits of this protein. In particular, the N‐terminus of the squid visual G‐γ contains a repetitive, highly charged region, rich in lysine and glutamate, that has no parallel in other G‐proteins. The amino acid sequence of a number of peptides derived by chemical cleavage of G‐γ accounted for much of the protein sequence predicted from the cDNA, including the unusual N‐terminal region.

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G protein gene expression during mouse oocyte growth and maturation, and preimplantation embryo development

1996

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G protein diversity is increased by associations with a variety of gamma subunits.

Cited by 112 publications

References 32 publications

Differential Ability to Form the G Protein βγ Complex among Members of the β and γ Subunit Families

Differential Ability to Form the G Protein βγ Complex among Members of the β and γ Subunit Families

The γ‐subunit of the principal G‐protein from squid (Loligo forbesi) photoreceptors contains a novel N‐terminal sequence

G protein gene expression during mouse oocyte growth and maturation, and preimplantation embryo development

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