Isolation of cDNA Clones Encoding Eight Different Human G Protein γ Subunits, Including Three Novel Forms Designated the γ4, γ10, and γ11 Subunits (∗)

• Published in: The Journal of biological chemistry 1995-09, Vol.270 (37), p.21765-21771
• Main Authors: Ray, Kausik, Kunsch, Charles, Bonner, Laura M., Robishaw, Janet D.
• Format: Article
• Language: English
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.270.37.21765

With the growing awareness that the G protein β and γ subunits directly regulate the activities of various enzymes and ion channels, the importance of identifying and characterizing these subunits is underscored. In this paper, we report the isolation of cDNA clones encoding eight different human γ subunits, including three novel forms designated γ4, γ10, and γ11. The predicted protein sequence of γ4 shares the most identity (60-77%) with γ2, γ3, and γ7 and the least identity (38%) with γ1. The γ4 is modified by a geranylgeranyl group and is capable of interacting with both β1 and β2 but not with β3. The predicted protein sequence of γ10 shows only modest to low identity (35-53%) with the other known γ subunits, with most of the differences concentrated in the N-terminal region, suggesting γ10 may interact with a unique subclass of α. The γ10 is modified by a geranylgeranyl group and is capable of interacting with β1 and β2 but not with β3. Finally, the predicted protein sequence of γ11 shows the most identity to γ1 (76% identity) and the least identity to the other known γ (33-44%). Unlike most of the other known γ subunits, γ11 is modified by a farnesyl group and is not capable of interacting with β2. The close resemblance of γ11 to γ1 raises intriguing questions regarding its function since the mRNA for γ11 is abundantly expressed in all tissues tested except for brain, whereas the mRNA for γ1 is expressed only in the retina where the protein functions in phototransduction.