Membrane components

Thomas Chimento chimento at ursa.arc.nasa.gov
Mon May 10 12:05:10 EST 1993


In article <C6oE3u.Fzu at news2.cis.umn.edu>, eichler at s21.msi.umn.edu (Rogene Eichler [mf12801]) writes:
|> 
|> Does anyone have references that might suggest an estimate in 
|> lipid/non-lipid ratio in nerve cell membrane? Any membrane, 
|> for that matter...
|> 

I think a better way to approach this problem is to ask " what is the density of membrane channels in a nerve cell". This is not an easy question to answer, partly because it will vary across cell types and is very dependent on location on any given cell. In Ionic Channels of Excitable Membranes by Bertil Hille (Sinauer Assoc. 1992) pp515 the muscle membrane concentration of acetylcholine recptors varies from 20,000/square micron where the motormeuron makes contact to  as low as 6-22/square micron elsewher

e. For nonmyelinated axons 35 to 500 Na+ channels per square micron of membrane has been measured. This works out to be about one Na+ channel in 4000 membrane molecules (Principles of Neural Science Kandel and Schwartz, Elsevier, 1985 pp. 82). 

If this is the type of answer you are looking for, let me know the final outcome, because I too need a long list of such densities, and they are not easy to find.
Thanks.

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