LIU, H.-F.; LAI, C.-Y.; ZHENG, J.*; WATSON, R.D.; LEE, C.-Y.; National Changhua University of Education, Taiwan, Republic of China; University of Alabama at Birmingham: Molecular Cloning of a Guanylyl Cyclase From Muscle of the Crayfish (Procambarus clarkii) and Y-Organs of the Crab (Callinectes sapidus)

Cyclic GMP (cGMP) acts as an intracellular second messenger mediating the actions of hormones and neurotransmitters. Synthesis of cGMP is catalyzed by guanylyl cyclase (GC). Based on their cellular distribution and structure, GC family enzymes are classified as either soluble form or membrane form. Crustacean hyperglycemic hormone (CHH) is a peptide hormone originally identified in a crustacean neurosecretory complex, the X-organ/sinus gland. Existing data suggest CHH is pleiotropic in its regulatory functions. Thus, CHH has been implicated in the regulation of carbohydrate metabolism, and other physiological processes, including molting, osmoregulation, and reproduction. Previous results suggest the effects of CHH are mediated, at least in part, by cGMP. We report here the cloning of a cDNA encoding a GC from muscle of the crayfish, Procambarus clarkii. The cDNA (PcGC-M2) encodes a protein with the signature domains characteristic of a membrane form GC. 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 PcGC-M2 transcript is expressed in several CHH target tissues. We hypothesize that the cloned cDNA encodes a CHH receptor. In related studies, we have also cloned a partial cDNA encoding a GC from Y-organs of the crab, Callinectes sapidus. The full sequence and tissue distribution of this cDNA remain to be determined. Supported by the National Science Council, Taiwan, Republic of China (fellowship 39175F and grant NSC-91-2311-B-018-002) and the National Science Foundation (IBN-0213047).