Sphingolipids presence/content

Therefore, if the recipient cell does not express the specific lipids required by the receptor (which may concern the acyl chain content of sphingolipids), or an adequate cholesterol-sphingolipid balance, the transfection experiment may lead to an abxmdant expression of a totally inactive receptor. In 2003, Opekarova and Tanner published a list of more than 30 membrane proteins whose activity is specifically affected by lipids. The list covered a broad range of proteins expressed by various bacteria, yeasts, insect, and mammalian cells. The problem is particularly acute when mammalian receptors or transporters are expressed in bacteria. For instance, the failure to express fxmctional serotonin transporters in E. coli has been attributed to the lack of cholesterol in bacteria. Moreover, the recovery of fully active neurotensin and adenosine receptors in transfected bacteria required the presence of choles-teryl hemisuccinate (a cholesterol derivative) during solubilization. Paradoxical results have also been obtained for some proteins whose activity requires cholesterol but can be fxmctionally expressed in bacterial hosts. In this case, one can exclude a direct interaction of cholesterol with the protein but rather consider a more general effect of the sterol on membrane properties. As a matter of fact, we are just at the beginning of our comprehension of the complex molecular ballet that involves bofh lipid and protein actors in the plasma membrane of excitable cells. 

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