Maybe here do you could info about your question .

http://www.binasss.sa.cr/revistas/rccm/v16n3/art8.pdf

http://bacmap.wishartlab.com/organisms/791

The outer membrane bilayer consists of an inner leaflet composed of ordinary phospholipids and an outer leaflet composed of lipopolysaccharide, of which lipid A is the membrane part. There are also proteins embedded in the outer membrane. The main problem with simulating the outer membrane lipid with liposomes is the asymmetry: How do you make the inner and outer leaflets out of different lipids?

Here is a paper in which asymmetric lipid bilayers were made:

http://rsif.royalsocietypublishing.org/content/10/89/20130810

Thank you very much. It's really helpful. I actually wanted to know the lipid A content in the plasma membrane not the outer membrane. If there is anyone who might have separated the two membranes and doe lipid content analysis of plasma membrane?  

Lipid A is found in the outer membrane. The cytoplasmic membrane consists of ordinary phospholipids. However, there is probably a little bit of lipid A in the inner membrane at any given time because it is made there and then transported to the outer membrane by the lipopolysaccharide transport system (LptABCDE).

Yes exactly, I am working on a lipid flippase and therefore, required to know the content of lipid A in the plasma membrane which I know will be very small before its flipping to OM. I have found literature where the total content of lipid A is quantified as approximately 10% wrt to glycerophospholipids but I can not find the approximate percentage in the plasma membrane itself.