Inositol-tetrakisphosphate 1-kinase, also known as ITPK1, is a 414 amino acid monomer that belongs to the ITPK1 family and exists as two alternatively spliced isoforms. ITPK1 is found at highest levels in brain, followed by heart, skeletal muscle, kidney, pancreas, liver, placenta and lung. ITPK1 contains one ATP-grasp domain and has been found to phosphorylate various inositol polyphosphates and modify TNFα induced apoptosis.