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Published April 5, 1985 | public
Journal Article

Sequence of the Alpha Subunit of Photoreceptor G Protein: Homologies between Transducin, ras, and Elongation Factors


A bovine retinal complementary DNA clone encoding the alpha subunit of transducin (T alpha) was isolated with the use of synthetic oligodeoxynucleotides as probes, and the complete nucleotide sequence of the insert was determined. THe predicted protein sequence of 354 amino acids includes the known sequences of four tryptic peptides and sequences adjacent to the residues that undergo adenosine diphosphate ribosylation by cholera toxin and pertussis toxin. On the basis of homologies to other proteins, such as the elongation factors of protein synthesis and the ras oncogene proteins, regions are identified that are predicted to be acylated and involved in guanine nucleotide binding and hydrolysis. Amino acid sequence similarity between T alpha and ras is confined to these regions of the molecules.

Additional Information

© 1985 American Association for the Advancement of Science. Received 22 January 1985; accepted 9 February 1985. We thank Jeremy Nathans for providing the retinal cDNA library, Suzanna Horvath for synthesis of oligodeoxynucleotides, and Ryn Miake-Lye for primer-extended M13 probes. Supported by NSF grant PCM 8410039 (M.S.), a Helen Hay Whitney fellowship (J.H.), and an NSF graduate fellowship (M.L.).

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August 19, 2023
October 19, 2023