Talk:Lipid raft

I'm not really convinced about the existence of lipid rafts. I'm not really sure what they are.

Their existence is still debated. A good recent review on the subject is from Sean Munro: Lipid rafts: elusive or illusive? Cell. 2003 Nov 14;115(4):377-88. Cjb88 20:14, 24 Jan 2005 (UTC)

I am a 4th-year biomedical engineering student at the University of Virginia currently working on imaging the surface of lipid rafts and obtaining some of their mechanical properties. I added some background information on lipid rafts that I've come across over the past few months. Sonrisa102 21:09, 13 December 2005 (UTC)

"Also because of this difference in saturation levels, the raft areas exhibit a higher melting point than the surrounding phospholipids." This statement is speculation, how is it possible to prove this? DSC will not show this.Rvlaw

"In addition, the increased concentration of cholesterol in the rafts further increases their rigidity." Again - what does "rigidity" mean in terms of a fluid? Does the author mean viscosity?Rvlaw

"part of the membrane (Henderson et al, 2004). Lipid rafts also differ from the rest of the membrane in that they are resistant to non-ionic detergents, such as Triton X-100. When the detergent is added to cells, the fluid membrane will associate into solution while the lipid rafts will remain in tact and can be extracted. Because of their composition and detergent resistance, lipid rafts may also be referred to as detergent-insoluble, glycolipid-enriched complexes, or DIGs (Dietrich & Jacobson, 1999). However, the validity of the detergent resistance methodology of membranes has recently been called into question. (Heerklotz, 2002)"

Not sure why this was removed. Whilst I agree that this technique is now seen as problematic, it was the basis of the technique from the beginningRvlaw 20:56, 14 January 2006 (UTC)

"A two-dimensional lipid bilayer may exist in a liquid or solid phase depending on whether the temperature is above or below the lipid melting temperature. In the solid phase, the lipids are immobile, packed tightly and with their hydrocarbon taild hightly ordered. As the temperature is increases a phase transition occurs and the packing becomes more loose and the lipids become more mobile. In the presence of cholesterol however a third phase is possible - the liquid-ordered phase. Cholesterol imposes order on near by tails allowing the lipids to remain mobiole but be tightly packed. This process is facilitated if the lipids contain highly saturated tails such as those found in sphingolipids." -This information is already found in the links.Rvlaw

"caused by the missmatch in the length of the hydrophobic tails arrising due to the packing and differences in saturation."Rvlaw - This is not the only cause of fluid-fluid immiscibility

Image

Sorry about the layout... I'm not able at all. May someone correct it?

thanks a lot!!

Role of rafts

I think this page could really do with a section summarising the role of rafts in cells. e.g. discussion of T cell receptor localisation and signalling, hijacking of cell signalling by bacteria such as Salmonella using rafts domains in the host cell etc. 82.211.95.178 10:34, 30 August 2007 (UTC)

sphingolipid tails

Hi. In the topmost figure (with the blue background), why are the sphingolipids shown as having three hydrocarbon chains in the tail instead of two? Kenmcl2 (talk) 21:31, 4 December 2007 (UTC)

because they are super sphingolipids. your right, it should be 2 —Preceding unsigned comment added by 66.130.90.42 (talk) 18:32, 10 April 2008 (UTC)