Linked Life Data

16042615

Source:http://linkedlifedata.com/resource/pubmed/id/16042615

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
Pt 4
pubmed:dateCreated
2005-7-26
pubmed:abstractText
Phototaxis and photophobic responses of green algae are mediated by rhodopsins with microbial type chromophores, i.e. all-trans-retinal in the ground state. The green alga Chlamydomonas reinhardtii was recently completely sequenced and the EST (expressed sequence tag) database was made public. We and others detected overlapping partial cDNA sequences that encode two proteins which we termed channelopsins (Chops). The N-terminal half of chop1 (approximately 300 of 712 amino acids) comprises hypothetical seven-transmembrane segments with sequence similarity to the proton pump bacteriorhodopsin and the chloride pump halorhodopsin. Even though the overall sequence homology is low, several amino acids are conserved that define the retinal-binding site and the H+-transporting network in BR (bacteriorhodopsin). Expression of Chop1, or only the hydrophobic core, in Xenopus laevis oocytes, enriched with retinal, produced a light-gated conductance (maximum at approx. 500 nm), which shows characteristics of a channel [ChR1 (channelrhodopsin-1)] that is selectively permeable for protons. Also ChR2 (737 amino acids) is an ion channel that is switched directly by light and also here the hydrophobic N-terminal half of the protein is sufficient to enable light-sensitive channel activity. The action spectrum is blue-shifted (maximum at approx. 460 nm) with respect to ChR1. In addition to protons, ChR2 is permeable to univalent and bivalent cations. We suggest that ChRs are involved in phototaxis of green algae. We show that heterologous expression of ChR2 is useful to manipulate intracellular pCa or membrane potential of animal cells, simply by illumination.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0300-5127
pubmed:author
pubmed:issnType
Print
pubmed:volume
33
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
863-6
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2005
pubmed:articleTitle
Channelrhodopsins: directly light-gated cation channels.
pubmed:affiliation
Max-Planck-Institut für Biophysik, Max-von-Laue-Strasse 3, 60438 Frankfurt, Germany. Georg.Nagel@botanik.uni-wuerzburg.de
pubmed:publicationType
Journal Article, Review, Research Support, Non-U.S. Gov't