Guanylyl cyclase C (GCC, or GUCY2C; MIM 601330) produces cGMP following the binding of either endogenous ligands or heat-stable enterotoxins secreted by E. coli and other enteric bacteria. Activation of GCC initiates a signaling cascade that leads to phosphorylation of the cystic fibrosis transmembrane conductance regulator (CFTR; MIM 602421), followed by a net efflux of ions and water into the intestinal lumen. IKEPP is a regulatory protein that associates with GCC and regulates the amount of cGMP produced following receptor stimulation (Scott et al., 2002 [PubMed 11950846]).[supplied by OMIM, Mar 2008]