Diphosphoinositol Pentakisphosphate Kinase 2 (PPIP5K2)

Inositol phosphates (IPs) and diphosphoinositol phosphates (PP-IPs), also known as inositol pyrophosphates, act as cell signaling molecules. HISPPD1 has both IP6 kinase (EC 2.7.4.21) and PP-IP5 (also called IP7) kinase (EC 2.7.4.24) activities that produce the high-energy pyrophosphates PP-IP5 and PP2-IP4 (also called IP8), respectively.

The deduced 1,243-amino acid protein had an apparent molecular mass of more than 100 kD by SDS-PAGE.The deduced 1,222-amino acid PPIP5K2 protein has a calculated molecular mass of 138 kD. It shares 66% amino acid identity with rat and human PPIP5K1, with most divergence occurring in the C termini. VIP2 also showed kinase activity in human embryonic kidney cells engineered to produce high levels of IP6 and 5-PP-IP5.