Journal of Lipid Research, Vol 23, 405-409, Copyright © 1982 by Lipid Research, Inc.
Isolation and characterization of filipin-resistant LM cell variants not auxotrophic for sterol
DA Rintoul, N Neungton and DF Silbert
A series of LM cell variants resistant to filipin, but not auxotrophic for
sterol, was isolated by plating mutagenized, filipin-treated cells on soft
agar medium containing no sterol. Cloned variants were assayed for growth
in the presence and absence of sterol or unsaturated fatty acid.
Filipin-resistant clones whose growth rate was unaffected by the addition
of sterol to the medium were further analyzed. Variants were cultured in
minimal medium, and plasma membranes prepared from these cultures were
analyzed for sterol content, phospholipid head group composition, and
unsaturated fatty acyl content. All variants examined showed a decrease in
membrane sterol in conjunction with an increase in unsaturated fatty acyl
chains in the membrane phospholipids. In addition, several variants
exhibited alterations in phospholipid head group composition, including
changes in the phosphatidylcholine/phosphatidylethanolamine ratio, or a
decrease in sphingomyelin content. These observations imply that several
different metabolic lesions can give rise to decreased plasma membrane
sterol content (and hence to filipin resistance). The range of phospholipid
alterations observed in these sterol prototrophs emphasizes the complex
interrelationship between membrane sterol and phospholipid structure.
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
