Identification of a region in G protein γ subunits conserved across species but hypervariable among subunit isoforms |
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Authors: | Lana A Cook Kevin L Schey John H Cleator Michael D Wilcox Jane Dingus and John D Hildebrandt |
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Institution: | Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, Charleston, South Carolina 29425, USA. |
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Abstract: | The heterotrimeric GTP binding proteins, G proteins, consist of three distinct subunits: alpha, beta, and gamma. There are 12 known mammalian gamma subunit genes whose products are the smallest and most variable of the G protein subunits. Sequencing of the bovine brain gamma(10) protein by electrospray mass spectrometry revealed that it differs from the human protein by an Ala to Val substitution near the N-terminus. Comparison of gamma isoform subunit sequences indicated that they vary substantially more at the N-terminus than at other parts of the protein. Thus, species variation of this region might reflect the lack of conservation of a functionally unimportant part of the protein. Analysis of 38 gamma subunit sequences from four different species shows that the N-terminus of a given gamma subunit isoform is as conserved between different species as any other part of the protein, including highly conserved regions. These data suggest that the N-terminus of gamma is a functionally important part of the protein exhibiting substantial isoform-specific variation. |
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Keywords: | G proteins γ subunit γ 10 mass spectrometry |
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