This gene encodes a dual functional inositol kinase. The encoded enzyme converts inositol hexakisphosphate to diphosphoinositol pentakisphosphate and diphosphoinositol pentakisphosphate to bis-diphosphoinositol tetrakisphosphate. This protein may be important for intracellular signaling pathways. Alternate splicing results in multiple transcript variants. A pseudogene of this gene is found on chromosome 15.[provided by RefSeq, Jun 2010].