Probably by regulating inositol 1,4,5-trisphosphate levels, negatively regulates posterior body wall muscle contractions required for defecation and let-23 signaling pathway that controls spermathecal dilation and ovulation (PubMed:9491893, PubMed:16186564). May also regulate ovulation downstream of actin cross-linker fln-1 (PubMed:23671426). 1D-myo-inositol 1,4,5-trisphosphate + ATP = 1D-myo-inositol 1,3,4,5-tetrakisphosphate + ADP + H(+) Unlike mammalian IP3K, may not be regulated by calmodulin. Expressed in spermatheca. Belongs to the inositol phosphokinase (IPK) family.