Abstract
Available data indicate that crustacean hyperglycemic hormone (CHH) stimulates membrane‐bound guanylyl cyclase (GC), producing cyclic guanosine 3′,5′–monophosphate, which in turn mediates the effect of CHH on carbohydrate metabolism. In the present study, we report the cloning of a cDNA (PcGC‐M2) encoding a putative membrane form GC from the muscle of the crayfish, Procambarus clarkii. Analysis of the deduced amino acid sequence shows that PcGC‐M2 contains the signature domains characteristic of membrane form GCs, including an extracellular ligand‐binding domain, a single transmembrane, and intracellular kinase‐like and cyclase catalytic domains. In addition, a C‐terminal domain of 247 residues is present following the cyclase catalytic domain. PcGC‐M2 is most closely related (33% identity) to a Drosophila membrane form GC (DrGC–1), and an Anopheles gambiae membrane form GC (AgaGC); the three GCs also share a similar distribution pattern of conserved cysteine residues in the extracellular domain. The PcGC‐M2 transcript is expressed in several CHH target tissues, including muscle, hepatopancreas, heart, ovary, testis, and gill, suggesting that PcGC‐M2 may participate in the signaling cascade activated by CHH. J. Exp. Zool. 301A:512–520, 2004. © 2004 Wiley‐Liss, Inc.