Fig. 1. The primary pathways of 1,5-InsP8 synthesis and metabolism. The graphic incorporates a proposal7,61 that the pathway for 1,5-InsP8 turnover comprises a predominantly cyclical interconversion of InsP6, 5-InsP7, 1,5-InsP8, and 1-InsP7. IP6K = inositol hexakisphosphate 5-kinase; PPIP5K = diphosphoinositol pentakisphosphate 1-kinase (this enzyme also possesses an active 1,5-InsP8 1-phosphatase activity); DIPP = diphosphoinositol polyphosphate phosphatase.
