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. Author manuscript; available in PMC: 2008 Sep 23.
Published in final edited form as: J Biol Chem. 1999 Apr 16;274(16):11139–11149. doi: 10.1074/jbc.274.16.11139

Fig. 5. Linearity of the partially purified 4′-phosphatase and phosphotransferase reactions with time.

Fig. 5

Partially purified enzyme (heparin-agarose step) was assayed for the 4′-phosphatase activity in the absence of PtdIns (open circles and squares) or for the phosphotransferase activity in the presence of PtdIns (closed circles and squares). Protein concentrations of 0.6 μg/ml (circles) or 1.2 μg/ml (squares) were used, and the assays were incubated at 30 °C for the indicated times under standard conditions (30 μl final volume). At every time point indicated, a 2-μl portion of the reaction mixture was withdrawn and analyzed by thin layer chromatography and PhosphorIm-ager analysis, as described under “Experimental Procedures.” The 4′-phosphatase activity is expressed as the amount of inorganic phosphate released per ml of reaction mixture in absence of PtdIns, while the phosphotransferase activity is expressed as the amount of PtdIns-4-P formed in the presence of PtdIns.