I was wondering if anyone has come across membrane lipids that have 3 or more hydrophobic tails. I was thinking along the oxidised phospholipids in disease that might incorporate more tails but need your suggestions if anyone know about this area
Hello Abbas,
Wojciech is right and cardiolipin is a standard lipid of 4 chains. Interestingly, that lipid is involved in apoptosis, and therefore diseases related to it (Here is a review in the issue, although there are more
http://www.sciencedirect.com/science/article/pii/S0005273609001618)
Also, if you go the website of Avanti Polar Lipids, there are modified lipids you can use. One example is Monolyso-cardiolipin, where one of the acyl chains of cardiolipin has been lost, therefore having 3 acyl chains (http://www.avantilipids.com/index.php?option=com_content&view=article&id=335&Itemid=308&catnumber=850081)
Abbas, I find questions like yours very interesting. They always make me wonder if Google or Pubmed does not work from posters computers!
😄
Furthermore, glycolipids typically have more than two chains.
Lipid A (being the main hydrophobic part of lipopolysaccharide or LPS) has six chains, for example, which can be cleaved-off by hydrolysis, or by specialised enzymes. Artificial glycolipids can be made with three chains as well.
In addition to cardiolipin, Schiff-base lipids and Lipid A, N-acylphosphatidylethanolamines, another group of three chain lipids are also found in nature. These molecules are especially interesting as their content in various organisms increases dramatically under different types of stress (see for a review on the N-acyl PEs, http://www.sciencedirect.com/science/article/pii/S0009308410000046).
The first is cardiolipin which undergoes significant acyl chain remodeling that may be due to the highly oxidative environment in which it is found in the inner mitochondrial membrane.
So, that is the first obvious choice in the mammalian system and is generally tetra-18:2 with two phosphates in muscle and heart, although we were one of the first groups to report its acyl chain composition in the brain as well as some kinetics for synthesis/remodeling done in vivo.
A lipid not mentioned is TAG (triacylglycerol) found in lipid droplets in a lot of cells.
I concur with Musti regarding the N-acylPE and other such modifications that can exist. However, these molecules do not have a bulk lipid effect as perhaps cardiolipin in the mitochondria.
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