Linked Life Data

6305023

Source:http://linkedlifedata.com/resource/pubmed/id/6305023

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
12
pubmed:dateCreated
1983-7-8
pubmed:abstractText
About 2000 PDE molecules are gradually activated by one bleached rhodopsin molecule, R* on a toad disk membrane to yield a final enzyme velocity of about 2.5 x 10(6) cGMP hydrolyzed sec-1 bleached rhodopsin-1. This amplified effect of a single photon requires GTP, whose function we originally proposed (Yee and Liebman, 1978; Liebman and Pugh, 1979) to serve as a "memory" label attached to each PDE as it is contacted via lateral diffusion by R*. Thus, the binding of GTP was explicitly seen as an identically-amplified casual link in the amplified PDE activation. We have subjected our GTP-PDE coupling hypothesis to both stoichiometric and kinetic tests using radioactive GTP labelling techniques. We find agreement in principle with our original hypothesis with modifications to allow for (1) GTP binding to a separate G-protein (gamma) which activates PDE; (2) evidence that there are fewer PDE's activated than GTP's bound in response to a light flash; (3) evidence of reversible binding of gamma to PDE with incomplete activation of the latter; (4) multisecond delay of GTP binding compatible with lateral diffusionally-mediated activation of thousands of gamma's by single R*'s; (5) gain regulation by ATP that reduces both PDE activation and GTP binding.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:issn
0042-6989
pubmed:author
pubmed:issnType
Print
pubmed:volume
22
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1475-80
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed:year
1982
pubmed:articleTitle
Gain, speed and sensitivity of GTP binding vs PDE activation in visual excitation.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.