Talk:Opsin

Merging?

This article should be merged with rhodopsin. Any thoughts? —Preceding unsigned comment added by Biophys (talk • contribs) 19:43, 5 September 2007 (UTC)

I'd recommend against the merge. The relationships among the opsins are complex, and can be better explained with separate articles. --Arcadian 22:29, 5 September 2007 (UTC)

Perhaps you are right, I left my notice about merging in rhodopsin. I did not know about four photopsins in humans (one of them is not in SwissProt?).Biophys 00:53, 10 September 2007 (UTC)

Merging again?

Should we merge the opsin article with the retinylidene protein article? If not what is the difference between the two? --kupirijo (talk) 15:21, 5 May 2011 (UTC)

First sentence is not general enough

The first sentence of the article (Opsins are a group of light-sensitive 35-55 kDa membrane-bound G protein-coupled receptors of the retinylidene protein family found in photoreceptor cells of the retina) refers to the animal rhodopsin not a general opsin protein. --kupirijo (talk) 15:22, 5 May 2011 (UTC)

No plant opsins?

The article says, there are Type 1 and Type 2 opsins, present in animals and prokaryotes. What about microbial-type rhodopsins that are in plants (C. reinhardtii)? — Preceding unsigned comment added by 85.178.76.207 (talk) 19:49, 11 August 2011 (UTC)

C. reinhardtii isn't a plant, but it is a eukaryote. I haven't come across plants that have them yet, but this isn't my field;) A fungus has a type I proton-gradient forming opsin (http://www.pnas.org/content/102/19/6879.full)

Type I opsins

citation 5 does not really cover type I opsins (what little it does cite/address mainly concerns phototaxis in eukaryotic systems). Citation 10 within (Soppa, J. Two hypotheses—one answer. Sequence comparison does not support an evolutionary link between Halobacterial retinal proteins including bacteriorhodopsin and eukaryotic G protein-coupled receptors. FEBS Lett. 342, 7–11 (1994).) is probably a better source for type I to type II comparisons. — Preceding unsigned comment added by 146.186.85.64 (talk) 18:31, 31 August 2011 (UTC)

Prokaryotic (type 1) opsins

The current evidence is inconclusive if the energy from Type I opsins can be used to fix CO2. All known archaea that have bacteriorhodopsin are photoheterotrophic (reliant on outside carbon sources). Bergey's says "CO2 fixation by halobacteria has been demonstrated on a number of occasions, but is believed to be due to several different anaplerotic mechanisms (danon and caplan 1977, javor 1988, rajagopalan and altekar 1991)." (perhaps not a direct quote). They went on to say something about RuBISCO being present, but at sub-relevant levels to cellular function (whatever that means) and referenced rajaopalan and altekar 1990. Around the time the 2001 edition of Bergey's came out, there was a 2000 paper from Beja's lab that said there MIGHT be autotrophy in the seas from proteorhodopsin, but later studies have shown there is a minimal increase in growth when light is around, and it doesn't seem to be autotrophic

Pagelm (talk) 18:38, 15 November 2011 (UTC)