Linked Life Data

1905955

Source:http://linkedlifedata.com/resource/pubmed/id/1905955

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
27
pubmed:dateCreated
1991-8-12
pubmed:abstractText
Absorption of a photon by the visual pigment rhodopsin leads to the formation of an activated conformational state, denoted rho*, which is capable of activating the visual G-protein, Gt. The bleaching of rhodopsin can be resolved into a series of spectrally distinct photointermediates. Previous studies suggest that the photointermediate metarhodopsin II (meta II, lambda max of 380 nm) corresponds to the physiologically active form rho*. In the studies reported herein, spectral and enzymological data were analyzed and compared so as to evaluate the temporal correspondence between meta II and rho*. This information was obtained by direct observation of the meta II and rho* decay times in parallel experiments utilizing identical preparations of urea-stripped, bovine retinal rod outer segment disk membranes at pH 8.0, 20 degrees C. Postflash spectra were deconvolved to resolve the meta II absorbance at 380 nm, and a decay time for the loss of meta II of 8.2 min (SD = 0.5 min) was obtained from fitting these data to a single-exponential decay process. The diminishing ability of bleached rhodopsin to activate Gt was measured by monitoring the level of catalyzed exchange of Gt-bound GDP for a nonhydrolyzable GTP analogue. Analysis of the decrease in the initial velocity of nucleotide exchange, measured at various postflash incubation times, yielded a rho* decay time of 7.7 min (SD = 0.5 min) when analyzed as a single-exponential process. The similarity of these decay times provides direct evidence that meta II and rho* are present over the same time regime, and further supports the equivalence of these two forms of photoactivated rhodopsin.(ABSTRACT TRUNCATED AT 250 WORDS)
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
9
pubmed:volume
30
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
6761-8
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1991
pubmed:articleTitle
Functional equivalence of metarhodopsin II and the Gt-activating form of photolyzed bovine rhodopsin.
pubmed:affiliation
Department of Biochemistry, University of Virginia Health Sciences Center, Charlottesville 22908.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.