The Bovine Photoreceptor Outer Segment Guanylate Cyclase: Purification, Kinetic Properties, and Molecular Size

Aparicio, Jennifer G.; Applebury, Meredithe L.

doi:10.1006/prep.1995.1067

Cited by 24 publications

(28 citation statements)

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“…This idea is supported by the fact that ATP decreases the K m for MgGTP from 2 mM to 1 mM. The latter value is the same as that measured for the purified enzyme in DDM in the absence of ATP (1.07 mM) (23). Finally, the interpretation is consistent with the function of ATP stimulation in other members of the family, which is thought to be mediated by the nucleotide binding site in the kinase homology domain and not via a factor present with the guanylate cyclases in membranes (20,22,43).…”

Section: Discussionsupporting

confidence: 65%

“…ROS Membranes and Guanylate Cyclase-Isolation of bovine ROS membranes, purification of the photoreceptor guanylate cyclase, and assay of guanylate cyclase activity were described previously (23). Washed membranes refer to ROS stripped of peripheral membrane proteins with a hypotonic buffer containing GTP (23).…”

Section: Materials-8-n 3 [␣-mentioning

confidence: 99%

“…Washed membranes refer to ROS stripped of peripheral membrane proteins with a hypotonic buffer containing GTP (23). Greater than 95% of the protein in purified preparations is guanylate cyclase; no other protein bands are visible when SDS gels containing 1 g of purified protein bands are Coomassie-stained (23).…”

Section: Materials-8-n 3 [␣-mentioning

confidence: 99%

“…b Data include use of both stripped and washed ROS membranes as defined in Aparicio and Applebury (23).…”

Section: Atp Stimulation Of Guanylatementioning

confidence: 99%

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The Photoreceptor Guanylate Cyclase Is an Autophosphorylating Protein Kinase

Aparicio¹,

Applebury²

1996

Journal of Biological Chemistry

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The membrane guanylate cyclase of vertebrate photoreceptor rod outer segments plays a key role in controlling the levels of cGMP, the intracellular second messenger that mediates visual signaling (1-5). In the dark-adapted photoreceptor, the resting cGMP levels are set by the balance of synthesis and degradation due to the basal activities of the guanylate cyclase and the cGMP phosphodiesterase. Throughout the processes of phototriggering, photorecovery, and light adaptation, the activity of the guanylate cyclase appears to be modulated to control cGMP levels. Several factors are known to regulate the guanylate cyclase activity. Intracellular calcium concentration in the range of 0.1 to 1 M inhibits cyclase activity in the presence of small calcium-binding proteins, GCAPs 1 (6 -8). In contrast, a protein of 40 kDa, composed of a multimer of 6 -7-kDa peptides, activates the cyclase in a calcium-dependent manner with halfmaximal activation occurring between 2 and 5 M (9). In addition, guanylate cyclase activity has been reported to be modulated by ATP (10, 11) and by protein kinase C (12). The calcium regulation mediated by GCAPs is thought to be responsible for cyclase activation during photorecovery and light adaptation; however, the physiological significance of regulation by the other factors is unclear. In all cases, the mechanisms by which these factors control the activity of the photoreceptor guanylate cyclase are not understood.The primary structure of the photoreceptor membrane guanylate cyclase has been deduced from cDNA sequences isolated from human, bovine, and rat retinas (13-15). 2 The information indicates that it is a member of the family of membrane guanylate cyclases that function as receptors for peptide ligands. Four functional domains are characteristic of these proteins: an amino-terminal "extracellular" domain, a transmembrane region, an intracellular protein kinase-like domain, and a carboxylterminal guanylate cyclase catalytic domain (17)(18)(19). In other members of the family, binding of peptide ligands to the extracellular amino-terminal domains induces stimulation of cytoplasmic guanylate cyclase activity. Molecules known to function in this manner include receptors for ANP (GC-A) and CNP (GC-B), guanylin and Escherichia coli enterotoxin (GC-C), and the sea urchin egg peptides, speract and resact. Although no ligand has been identified for the photoreceptor guanylate cyclase, its structural similarity to the receptor guanylate cyclases suggests that it may be regulated in a similar manner.In this work, we have focused on the role of the kinase-like domain of the photoreceptor guanylate cyclase. Studies of other members of the receptor guanylate cyclase family clearly indicate that the kinase homology domain is required to transduce the ligand-binding signals and activate the guanylate cyclases (20 -22). ATP is required for ligand-mediated activation, but nonhydrolyzable ATP analogues work as well (17). No kinase activity has been measured for any receptor guanylate cyclase, and autoph...

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Section: Discussionsupporting

confidence: 65%

Section: Materials-8-n 3 [␣-mentioning

confidence: 99%

Section: Materials-8-n 3 [␣-mentioning

confidence: 99%

“…b Data include use of both stripped and washed ROS membranes as defined in Aparicio and Applebury (23).…”

Section: Atp Stimulation Of Guanylatementioning

confidence: 99%

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The Photoreceptor Guanylate Cyclase Is an Autophosphorylating Protein Kinase

Aparicio¹,

Applebury²

1996

Journal of Biological Chemistry

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“…Although the localization of GC1 to rod and cone outer segments and synaptic terminals was established by both biochemical and immunocytochemical methods (5,(10)(11)(12)(13)(14), the localization of GC2 within photoreceptors is not known. Two GCAPs that stimulate GC1 and GC2 have also been cloned (15)(16)(17).…”

mentioning

confidence: 99%

Localization of guanylate cyclase-activating protein 2 in mammalian retinas

Otto‐Bruc

Fariss

Haeseleer

et al. 1997

Proc. Natl. Acad. Sci. U.S.A.

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A BSTR ACTGuanylate cyclase-activating proteins (GCAP1 and GCAP2) are thought to mediate the intracellular stimulation of guanylate cyclase (GC) by Ca 2؉ , a key event in recovery of the dark state of rod photoreceptors after exposure to light. GCAP1 has been localized to rod and cone outer segments, the sites of phototransduction, and to photoreceptor synaptic terminals and some cone somata. We used in situ hybridization and immunocytochemistry to localize GCAP2 in human, monkey, and bovine retinas. In human and monkey retinas, the most intense immunolabeling with anti-GCAP2 antibodies was in the cone inner segments, somata, and synaptic terminals and, to a lesser degree, in rod inner segments and inner retinal neurons. In bovine retina, the most intense immunolabeling was in the rod inner segments, with weaker labeling of cone myoids, somata, and synapses. By using a GCAP2-specific antibody in enzymatic assays, we confirmed that GCAP1 but not GCAP2 is the major component that stimulates GC in bovine rod outer segment homogenates. These results suggest that although GCAP1 is involved in the Ca 2؉ -sensitive regulation of GC in rod and cone outer segments, GCAP2 may have non-phototransduction functions in photoreceptors and inner retinal neurons.In photoreceptor cells, photoactivation of rhodopsin or cone visual pigment results in a transient decrease in the concentrations of Ca 2ϩ and cGMP. These receptors and second messengers are linked through a cascade of specific activation͞ inactivation reactions in phototransduction (1, 2). The levels of Ca 2ϩ and cGMP are strictly controlled and interconnected. cGMP is a gating ligand of the plasma membrane cation channels that are permeable to Ca 2ϩ ions. After cGMP is hydrolyzed, the efflux of Ca 2ϩ exceeds the influx, resulting in decreased [Ca 2ϩ ] within the cell. The lowering of [Ca 2ϩ ] triggers production of cGMP through activation of a photoreceptor-specific particulate guanylate cyclase (GC) (3). The Ca 2ϩ sensitivity of GC (e.g., the higher activity at low levels of [Ca 2ϩ ]) is mediated by one or more Ca 2ϩ -binding proteins, termed guanylate cyclase-activating proteins (GCAPs) (4, 5).Two photoreceptor-specific GCs, GC1 and GC2, have been cloned (6-9). Although the localization of GC1 to rod and cone outer segments and synaptic terminals was established by both biochemical and immunocytochemical methods (5,(10)(11)(12)(13)(14), the localization of GC2 within photoreceptors is not known. Two GCAPs that stimulate GC1 and GC2 have also been cloned (15-17). There is abundant evidence that GCAP1 activates photoreceptor GC: (i) GCAP1 was isolated from rod outer segments (ROS) (4, 18); (ii) GCAP1 mRNA was found in the myoid region of rod and cone photoreceptor cells (15, 19); (iii) GCAP1 was localized to rod and cone outer segments and to some cone somata and synaptic terminals by immunocytochemistry (17, 18); (iv) cross-linking techniques revealed that GCAP1 was complexed with GC1 (20). In addition, the finding that GC1 is not expressed in the retina of the rd...

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Natriuretic Peptides

Bold¹,

Bruneau²

2000

Comprehensive Physiology

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The sections in this article are: Historical Perspectives Primary Structure Assay Methods The Endocrine Heart Functional Morphology Biological Properties of Natriuretic Peptides and Their Receptors Natriuretic Peptide Gene Structure Mechanical and Neuroendocrine Control of Natriuretic Peptide Gene Expression and Release Contribution of Natriuretic Peptides to Cardiovascular Homeostasis

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The Bovine Photoreceptor Outer Segment Guanylate Cyclase: Purification, Kinetic Properties, and Molecular Size

Cited by 24 publications

References 0 publications

The Photoreceptor Guanylate Cyclase Is an Autophosphorylating Protein Kinase

The Photoreceptor Guanylate Cyclase Is an Autophosphorylating Protein Kinase

Localization of guanylate cyclase-activating protein 2 in mammalian retinas

Natriuretic Peptides

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