Figure 4.

Phospholipids affect type III PtdIns 4-kinase activities. Sf9 insect cells expressing AtPI4Kα1 (A) and AtPI4Kβ1 (B) were harvested 2 (AtPI4Kβ1) and 3 (AtPI4Kα1) d after infection with recombinant baculovirus. Eight micrograms of the cleared lysates was assayed for PtdIns 4-kinase activity in the presence of increasing concentrations of PtdIns4P, PtdIns3P, PtdOH, PtdSer, and PtdCho. The lipids were prepared in 1% (v/v) Triton X-100, and the final concentrations of Triton X-100 and PtdIns in the PtdIns 4-kinase assay were kept constant at 0.2% (v/v) and 5.8 mm, respectively. Values are the average of duplicate samples of a representative experiment. Experiments from two independent recombinant baculovirus infections gave similar results.