The novel guanylyl cyclase MsGC-I is strongly expressed in higher-order neuropils in the brain of Manduca sexta

Guanylyl cyclases are usually characterized as being either soluble (sGCs) or receptor (rGCs), We have recently cloned a novel guanylyl cyclase, MsGC- I, from the developing nervous system of the hawkmoth Manduca sexta that ca nnot be classified as either an sGC or an rGC, MsGC-I shows highest sequenc e identity with receptor guanylyl cyclases throughout its catalytic and dim erization domains, but does not contain the ligand-binding, transmembrane o r kinase-like domains characteristic of receptor guanylyl cyclases. In addi tion, MsGC-I contains a C-terminal extension of 149 amino acid residues. In this paper, we report the expression of MsGC-I in the adult. Northern blot s show that it is expressed preferentially in the nervous system, with high levels in the pharate adult brain and antennae. In the antennae, immunohis tochemical analyses show that it is expressed in the cell bodies and dendri tes, but not axons, of olfactory receptor neurons. In the brain, it is expr essed in a variety of sensory neuropils including the antennal and optic lo bes. It is also expressed in structures involved in higher-order processing including the mushroom bodies and central complex. This complicated expres sion pattern suggests that this novel guanylyl cyclase plays an important r ole in mediating cyclic GMP levels in the nervous system of Manduca sexta.