Guanylate cyclase involved in the production of the second messenger cGMP (By similarity). GTP = 3',5'-cyclic GMP + diphosphate Expressed bilaterally in AWA and ASI sensory neurons and in RIA and PVT interneurons. The protein kinase domain is predicted to be catalytically inactive. Belongs to the adenylyl cyclase class-4/guanylyl cyclase family.