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Repetitive Segmental Structure of the Transducin β Subunit: Homology with the CDC4 Gene and Identification of Related mRNAs

Fong, Henry K. W. and Hurley, James B. and Hopkins, Rosemary S. and Miake-Lye, Ryn and Johnson, Mark S. and Doolittle, Russell F. and Simon, Melvin I. (1986) Repetitive Segmental Structure of the Transducin β Subunit: Homology with the CDC4 Gene and Identification of Related mRNAs. Proceedings of the National Academy of Sciences of the United States of America, 93 (7). pp. 2162-2166. ISSN 0027-8424. PMCID PMC323251. doi:10.1073/pnas.83.7.2162.

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Retinal transducin, a guanine nucleotide regulatory protein (referred to as a G protein) that activates a cGMP phosphodiesterase in photoreceptor cells, is comprised of three subunits. We have identified and analyzed cDNA clones of the bovine transducin β subunit that may be highly conserved or identical to that in other G proteins. From the cDNA nucleotide sequence of the entire coding region, the primary structure of a 340-amino acid protein was deduced. The encoded β subunit has a Mr of 37,375 and is comprised of repetitive homologous segments arranged in tandem. Furthermore, significant homology in primary structure and segmental sequence exists between the β subunit and the yeast CDC4 gene product. The Mr 37,375 β subunit polypeptide is encoded by a 2.9-kilobase (kb) mRNA. However, there exists in retina other β-related mRNAs that are divergent from the 2.9-kb mRNA on the basis of oligonucleotide and primer-extended probe hybridizations. All mammalian tissues and clonal cell lines that have been examined contain at least two β-related mRNAs, usually 1.8 and 2.9 kb in length. These results suggest that the mRNAs are the processed products of a small number of closely related genes or of a single highly complex β gene.

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Additional Information:© 1986 by the National Academy of Sciences. Contributed by Melvin I. Simon, November 19, 1985. We express sincere thanks to Drs. Breck Byers and John Yochem for communicating to us the sequence of the yeast CDC4 gene and Drs. Michael A. Lochrie for many helpful discussions and ideas, Jeremy Nathans for providing us with the bovine retinal cDNA library, Suzanna Horvath for synthesizing the oligodeoxynucleotides, David B. Teplow for assistance with the peptide sequence analysis, and Eric Phizicky for providing heptylagarose. This work was supported by Grant GM34236 from the National Institutes of Health. The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.
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Subject Keywords:guanine nucleotide regulatory protein; photoreceptor biochemistry; molecular evolution; signal transduction
Issue or Number:7
PubMed Central ID:PMC323251
Record Number:CaltechAUTHORS:FONpnas86
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:10285
Deposited By: Archive Administrator
Deposited On:22 Apr 2008
Last Modified:08 Nov 2021 21:06

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