The function of ITPKA (inositol-trisphosphate 3-kinase A, ENSG00000137825) is as follows. Catalyzes the phosphorylation of 1D-myo-inositol 1,4,5- trisphosphate (InsP3) into 1D-myo-inositol 1,3,4,5-tetrakisphosphate and participates to the regulation of calcium homeostasis. {ECO:0000269|PubMed:12747803, ECO:0000269|PubMed:15350214, ECO:0000269|PubMed:1847047}.