Switch to
| Predicate | Object |
|---|---|
| rdf:type | |
| lifeskim:mentions | |
| pubmed:issue |
9
|
| pubmed:dateCreated |
1996-5-28
|
| pubmed:abstractText |
In rhodopsin, the 11-cis-retinal chromophore forms a complex with Lys296 of opsin via a protonated Schiff base. Absorption of light initiates the activation of rhodopsin by cis/trans photoisomerization of retinal. Thermal relaxation through different intermediates leads into the metarhodopsin states which bind and activate transducin (Gt) and rhodopsin kinase (RK). all-trans-Retinal also recombines with opsin independent of light, forming activating species of the receptor. In this study, we examined the mechanism by which all-trans-retinal activates opsin. To exclude other amines except active site Lys296 from formation of Schiff bases, we reductively methylated rhodopsin (PM-rhodopsin), which we then bleached to generate PM-opsin. Using spectroscopic methods and a Gt activation assay, we found that all-trans-retinal interacted with PM-opsin, producing a noncovalent complex that activated Gt. The residual nucleotide exchange in Gt catalyzed by opsin was approximately 1/250 lower relative to that of photoactivated rhodopsin (pH 8.0, 23 degrees C). Addition of equimolar all-trans-retinal led to an occupancy of one-tenth of the putative retinal binding site(s) of opsin and enhanced the Gt activation rate 2-fold. When the concentration of all-trans-retinal was increased to saturation, the Gt activation rate of the opsin/all-trans-retinal complex was approximately 1/33 lower compared to that of photoactivated rhodopsin. We conclude that all-trans-retinal can form a noncovalent complex with opsin that activates Gt by different mechanisms than photolyzed rhodopsin.
|
| pubmed:grant | |
| pubmed:language |
eng
|
| pubmed:journal | |
| pubmed:citationSubset |
IM
|
| pubmed:chemical |
http://linkedlifedata.com/resource/pubmed/chemical/GTP-Binding Proteins,
http://linkedlifedata.com/resource/pubmed/chemical/Lysine,
http://linkedlifedata.com/resource/pubmed/chemical/Retinaldehyde,
http://linkedlifedata.com/resource/pubmed/chemical/Rhodopsin,
http://linkedlifedata.com/resource/pubmed/chemical/Rod Opsins,
http://linkedlifedata.com/resource/pubmed/chemical/Schiff Bases,
http://linkedlifedata.com/resource/pubmed/chemical/Transducin
|
| pubmed:status |
MEDLINE
|
| pubmed:month |
Mar
|
| pubmed:issn |
0006-2960
|
| pubmed:author | |
| pubmed:issnType |
Print
|
| pubmed:day |
5
|
| pubmed:volume |
35
|
| pubmed:owner |
NLM
|
| pubmed:authorsComplete |
Y
|
| pubmed:pagination |
2901-8
|
| pubmed:dateRevised |
2008-11-21
|
| pubmed:meshHeading |
pubmed-meshheading:8608127-Animals,
pubmed-meshheading:8608127-Binding Sites,
pubmed-meshheading:8608127-Cattle,
pubmed-meshheading:8608127-Darkness,
pubmed-meshheading:8608127-GTP-Binding Proteins,
pubmed-meshheading:8608127-Hydrogen-Ion Concentration,
pubmed-meshheading:8608127-Kinetics,
pubmed-meshheading:8608127-Light,
pubmed-meshheading:8608127-Lysine,
pubmed-meshheading:8608127-Methylation,
pubmed-meshheading:8608127-Photolysis,
pubmed-meshheading:8608127-Retinaldehyde,
pubmed-meshheading:8608127-Rhodopsin,
pubmed-meshheading:8608127-Rod Cell Outer Segment,
pubmed-meshheading:8608127-Rod Opsins,
pubmed-meshheading:8608127-Schiff Bases,
pubmed-meshheading:8608127-Spectrophotometry,
pubmed-meshheading:8608127-Stereoisomerism,
pubmed-meshheading:8608127-Transducin
|
| pubmed:year |
1996
|
| pubmed:articleTitle |
Opsin/all-trans-retinal complex activates transducin by different mechanisms than photolyzed rhodopsin.
|
| pubmed:affiliation |
Institut für Medizinische Physik und Biophysik, Charité, Humboldt-Universität zu Berlin, Ziegelstrasse 5-9, Germany.
|
| pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, P.H.S.,
Research Support, Non-U.S. Gov't
|