inositol 1,3,4,5-tetraphosphate

in·o·si·tol 1,3,4,5-·tet·ra·phos·phate

a phosphorylated derivative of inositol formed from inositol 1,4,5-trisphosphate that causes Ca2+ entry into the cytosol from the extracellular medium; inactivated by hydrolysis to form inositol 1,3,4-trisphosphate.