Identification of a Novel Guanylyl Cyclase That Is Related to Receptor Guanylyl Cyclases, but Lacks Extracellular and Transmembrane Domains*
- From the ‡Arizona Research Labs, Division of Neurobiology, The University of Arizona, Tucson, Arizona 85721 and the §Department of Biological Structure and Function, Oregon Health Sciences University, School of Dentistry, Portland, Oregon 97201-3097
Abstract
We have identified a novel guanylyl cyclase, named MsGC-I, that is expressed in the nervous system of Manduca sexta. MsGC-I shows highest sequence identity with receptor guanylyl cyclases throughout its catalytic and dimerization domains but does not contain the ligand-binding, transmembrane, or kinase-like domains characteristic of receptor guanylyl cyclases. In addition, MsGC-I contains a C-terminal extension of 149 amino acids that is not present in other receptor guanylyl cyclases. The sequence of MsGC-I contains no regions that show similarity to the regulatory domain of soluble guanylyl cyclases. Thus, MsGC-I appears to represent a member of a new class of guanylyl cyclases. We show that both a transcript and a protein of the sizes predicted from the MsGC-I cDNA are present in the nervous system of Manduca and that MsGC-I is expressed in a small population of neurons within the abdominal ganglia. When expressed in COS-7 cells, MsGC-I appears to exist as a soluble homodimer with high levels of basal guanylyl cyclase activity that is insensitive to stimulation by nitric oxide. Western blot analysis, however, shows that MsGC-I is localized to the particulate fraction of nervous system homogenates, suggesting that it may be membrane-associated in vivo.
Footnotes
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↵* This project was supported by grant number NS29740 from NINDS, National Institutes of Health and by grant 9604536 from National Science Foundation.The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
The nucleotide sequence(s) reported in this paper has been submitted to the GenBank™/EMBL Data Bank with accession number(s) AF073342.
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↵¶ To whom correspondence should be addressed: Dept. of Biological Structure and Function, Oregon Health Sciences University, School of Dentistry, 611 SW Campus Drive, SD, Portland, OR 97201-3097. Tel.: 503-494-8596; Fax: 503-494-8554; E-mail:mortonda{at}ohsu.edu.
- Abbreviations:
- NO
-
nitric oxide
- cGMP
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3′,5′-cyclic guanosine monophosphate
- GST
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glutathioneS-transferase
- SNP
-
sodium nitroprusside
- BCIP
-
5-bromo-4-chloro-3-indolyl phosphate
- kb
-
kilobases(s)
- GCAP
-
guanylyl cyclase activating protein.
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- Received July 23, 1998.
- Revision received September 28, 1998.
- The American Society for Biochemistry and Molecular Biology, Inc.
