Isolation of CERT-deficient HeLa cell clones.

A, Resistance to lysenin in HeLa TAL-CERT clones. The clones were treated with lysenin at 670 ng/ml for 2 h. Their viability was estimated by the MTT assay: mean percentage ± S.D. obtained from three independently repeated experiments. B, Indel analysis of CERT gene in TAL-CERT clones. Indels are shown in red and their lengths are specified on the right of the sequences. The predicted proteins are indicated based on the recommended description (see Materials and Methods) [50]. C, Protein levels of CERT in TAL-CERT clones. Arrow indicates CERT protein at 68 kD. D, Metabolic labeling of lipids with radioactive serine. TAL-CERT clones were cultured with [14C]serine for 16 h, and lipids extracted from the cells were separated by TLC. Radioactive image of an analyzed TLC plate is shown. PE, phosphatidylethanolamine; PS, phosphatidylserine; PC, phosphatidylcholine.