Identification of a novel guanylyl cyclase that is related to receptor guanylyl cyclases, but lacks extracellular and transmembrane domains

• Published in: The Journal of biological chemistry 1999-02, Vol.274 (7), p.4440-4446
• Main Authors: Simpson, P.J, Nighorn, A, Morton, D.B
• Format: Article
• Language: English
• Subjects: abdomen; Amino Acid Sequence; amino acid sequences; Animals; Blotting, Western; Calcium-Binding Proteins - chemistry; Calcium-Binding Proteins - metabolism; Catalytic Domain; Cell Membrane - chemistry; central nervous system; Cloning, Molecular; complementary DNA; COS Cells; Cyclic GMP - metabolism; Dimerization; enzyme activity; Extracellular Matrix - chemistry; ganglia; genbank/af073342; gene expression; guanylate cyclase; Guanylate Cyclase - chemistry; Guanylate Cyclase - genetics; Guanylate Cyclase - metabolism; Guanylate Cyclase-Activating Proteins; immunocytochemistry; Immunohistochemistry; Manduca - enzymology; Manduca sexta; messenger RNA; Molecular Sequence Data; Nerve Tissue Proteins - chemistry; Nerve Tissue Proteins - metabolism; Nervous System - enzymology; neurons; nucleotide sequences; Polymerase Chain Reaction; Sequence Analysis, DNA
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.274.7.4440

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 .