Isolation and characterization of cultured mammalian cell mutants defective in phospholipid biosynthesis

点击翻译按钮获取中文摘要

(1) We cloned two CHO cell genes that complement the mutation of PSA-3, a phosphatidylserine auxotrophic mutant of CHO cell line. (2) We examined the effects of the modification of membrane phospholipids on the proliferation of the sindbis virus in PSA-3 cells and found that when PSA-3 cells are grown without phosphatidylserine, the binding and internalization of the virus occur normally but the yield of virions and viral RNA synthesis greatly decreased. These results indicate that cellular phosphatidylserine and/or phosphatidylethanolamine participate in a certain step of sindbis virus infection, after the internalization of virus particles, but before penetration of the viral nucleocapsids into the cytoplasm. (3) We obtained a CHO cell mutant (# 29) which is defective in the regulation of phosphatidylserine biosynthesis. In this mutant cells, phosphatidylserine bisynthesis was elevated about two-fold and was remarkably resistant to the inhibition by exogenous phosphatidylserine as compared to the parental cells. (4) We found that CHO cells have two kinds of inositol transport systems, namely, sodium-dependent and sodium-independent systems. We obtained CHO cell mutants defective in sodium-dependent inositol transport system. (5) We isolated CHO cell mutants defective in glucose transport. In one of the mutants (GTS-31), the level of glucose transporter was reduced by 80% as compared to the parental cells.