title: Structural and biochemical identity of retinal rod outer segment membrane guanylate cyclase.
abstract: Recent molecular cloning reports show that there are at least three membrane guanylate cyclases in vertebrate retina: (1) atrial natriuretic factor receptor guanylate cyclase (ANF-RGC), (2) C-type natriuretic peptide receptor guanylate cyclase (CNP-RGC), and (3) "retinal guanylate cyclase" (RetGC). The specific cellular localization of the first two cyclases is unknown, but RetGC is apparently localized in photoreceptor cells, suggesting that it participates in visual transduction. With the overall objective of identifying the guanylate cyclase that is linked to phototransduction, we compared the structural and regulatory properties of the biochemically characterized 112 kDa bovine rod outer segment membrane guanylate cyclase (ROS-GC) with those of RetGC, ANF-RGC and CNP-RGC. The N-terminal and two internal peptide sequences of purified ROS-GC had about 90% similarity with the corresponding sequences of the RetGC; the sequence identity with natriuretic peptide receptor cyclases was about 30%. A 19 amino acid long sequence from a tryptic peptide of ROS-GC had no corresponding sequence in the other three cyclases. ROS-GC was inhibited by ATP but ANF-RGC and CNP-RGC were activated by ATP in the presence of the respective peptide hormones. These results suggest that ROS-GC represents a new subtype of the membrane guanylate cyclase family that is structurally and biochemically distinct from the other retinal cyclases.
authors.affiliation: Unit of Regulatory and Molecular Biology, Pennsylvania College of Optometry, Philadelphia 19141.
authors.forename: A
authors.initials: A
authors.lastname: Margulis
authors.forename: R M
authors.initials: RM
authors.lastname: Goraczniak
authors.forename: T
authors.initials: T
authors.lastname: Duda
authors.forename: R K
authors.initials: RK
authors.lastname: Sharma
authors.forename: A
authors.initials: A
authors.lastname: Sitaramayya
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D009320:Atrial Natriuretic Factor / Q000494:pharmacology; D002417:Cattle; D002460:Cell Line; D006162:Guanylate Cyclase / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D006801:Humans; D007527:Isoenzymes / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D020098:Natriuretic Peptide, C-Type; D009419:Nerve Tissue Proteins / Q000494:pharmacology; D017461:Receptors, Atrial Natriuretic Factor / Q000235:genetics; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D012374:Rod Cell Outer Segment / Q000201:enzymology*; D017386:Sequence Homology, Amino Acid; D014162:Transfection
chemical_list: D007527:Isoenzymes; D009419:Nerve Tissue Proteins; D011994:Recombinant Proteins; D020098:Natriuretic Peptide, C-Type; D009320:Atrial Natriuretic Factor; D000255:Adenosine Triphosphate; D006162:Guanylate Cyclase; D017461:Receptors, Atrial Natriuretic Factor; C073616:atrial natriuretic factor receptor C