Isolation, Separation, and Analysis of Phosphoinositides from Biological Sources

The phosphoinositides, namely phosphatidylinositol (PI), phosphatidylinositol 4-phosphate (PIP), and phosphatidylinositol 4,5-bisphosphate (PIP2), are acidic lipids that are present in all animal tissues. The markedly polar character of these lipids makes conventional lipid extraction and assay procedures unsuitable for their analysis. Hence, specific analytical procedures have been devised in a number of laboratories for the quantitative extraction, separation, and assay of this class of lipids. These methods are reviewed, and details of analytical procedures used in our laboratory are given below.