Phosphoinositides. 2. The inositol 1-phosphate structure in liver phosphatidylinositol.

The hydrolysis studies reported in the preceding paper (Hawthorne, 1960) suggest that in liver phosphatidylinositol the phosphate group is linked to one of the cis-hydroxyl groups of the inositol, i.e. to positions 1(3)or 2-. Until recently, the inositol monophosphate isolated from phosphoinositides was believed to be optically inactive (Iselin, 1949; Hawthorne, 1955) and so liver phosphatidylinositol was thought to have the 2-structure (Hawthorne & Hubscher, 1959 a). It can be seen from the structure (I) that only the 2or 5-phosphate has