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| Predicate | Object |
|---|---|
| rdf:type | |
| lifeskim:mentions | |
| pubmed:issue |
1
|
| pubmed:dateCreated |
1998-2-2
|
| pubmed:abstractText |
Guanylate cyclase-activating protein 1 (GCAP1), a photoreceptor-specific Ca2+-binding protein, activates retinal guanylate cyclase 1 (GC1) during the recovery phase of phototransduction. In contrast to other Ca2+-binding proteins from the calmodulin superfamily, the Ca2+-free form of GCAP1 stimulates the effector enzyme. In this study, we analyzed the Ca2+-dependent changes in GCAP1 structure by limited proteolysis and mutagenesis in order to understand the mechanism of Ca2+-sensitive modulation of GC1 activity. The change from a Ca2+-bound to a Ca2+-free form of GCAP1 increased susceptibility of Ca2+-free GCAP1 to proteolysis by trypsin. Sequencing data revealed that in the Ca2+-bound form, only the N-terminus (myristoylated Gly2-Lys9) and C-terminus (171-205 fragment) of GCAP1 are removed by trypsin, while in the Ca2+-free form, GCAP1 is readily degraded to small fragments. Successive inactivation of each of the functional EF loops by site-directed mutagenesis showed that only EF3 and EF4 contribute to a Ca2+-dependent inactivation of GCAP1. GCAP1(E75D,E111D,E155D) mutant did not bind Ca2+ and stimulated GC1 in a [Ca2+]-independent manner. GCAP1 and GCAP2, but not S-100beta, a high [Ca2+]free activator of GC1, competed with the triple mutant at high [Ca2+]free, inhibiting GC1 with similar IC50's. These competition results are consistent with comparable affinities between GC1 and GCAPs. Our data suggest that GCAP1 undergoes major conformational changes during Ca2+ binding and that EF3 and EF4 motifs are responsible for changes in the GCAP1 structure that converts this protein from the activator to the inhibitor of GC1.
|
| pubmed:grant | |
| pubmed:language |
eng
|
| pubmed:journal | |
| pubmed:citationSubset |
IM
|
| pubmed:chemical |
http://linkedlifedata.com/resource/pubmed/chemical/Calcium,
http://linkedlifedata.com/resource/pubmed/chemical/Calcium-Binding Proteins,
http://linkedlifedata.com/resource/pubmed/chemical/Guanylate Cyclase,
http://linkedlifedata.com/resource/pubmed/chemical/Guanylate Cyclase-Activating...,
http://linkedlifedata.com/resource/pubmed/chemical/S100 Proteins,
http://linkedlifedata.com/resource/pubmed/chemical/Trypsin
|
| pubmed:status |
MEDLINE
|
| pubmed:month |
Jan
|
| pubmed:issn |
0006-2960
|
| pubmed:author | |
| pubmed:issnType |
Print
|
| pubmed:day |
6
|
| pubmed:volume |
37
|
| pubmed:owner |
NLM
|
| pubmed:authorsComplete |
Y
|
| pubmed:pagination |
248-57
|
| pubmed:dateRevised |
2008-11-21
|
| pubmed:meshHeading |
pubmed-meshheading:9425045-Amino Acid Sequence,
pubmed-meshheading:9425045-Amino Acid Substitution,
pubmed-meshheading:9425045-Animals,
pubmed-meshheading:9425045-Binding, Competitive,
pubmed-meshheading:9425045-Calcium,
pubmed-meshheading:9425045-Calcium-Binding Proteins,
pubmed-meshheading:9425045-Cattle,
pubmed-meshheading:9425045-Cell Line,
pubmed-meshheading:9425045-Enzyme Activation,
pubmed-meshheading:9425045-Guanylate Cyclase,
pubmed-meshheading:9425045-Guanylate Cyclase-Activating Proteins,
pubmed-meshheading:9425045-Hydrolysis,
pubmed-meshheading:9425045-Insects,
pubmed-meshheading:9425045-Kinetics,
pubmed-meshheading:9425045-Molecular Sequence Data,
pubmed-meshheading:9425045-Mutagenesis, Site-Directed,
pubmed-meshheading:9425045-Photoreceptor Cells,
pubmed-meshheading:9425045-Protein Folding,
pubmed-meshheading:9425045-S100 Proteins,
pubmed-meshheading:9425045-Trypsin
|
| pubmed:year |
1998
|
| pubmed:articleTitle |
Changes in biological activity and folding of guanylate cyclase-activating protein 1 as a function of calcium.
|
| pubmed:affiliation |
Department of Ophthalmology, School of Medicine, University of Washington, Seattle 98195, USA.
|
| pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, P.H.S.,
Research Support, Non-U.S. Gov't
|