The crustacean hyperglycemic hormone precursors a and b of the Norway lobster differ in the preprohormone but not in the mature peptide

The neuro-endocrine X-organ sinus-gland complex of crustaceans produces and releases the neuropeptides of the crustacean hyperglycemic hormone (cHH)/molt-inhibiting hormone (MIH)/gonad-inhibiting hormone (GIH) family that regulate important physiological processes, such as growth, reproduction and molting. We cloned two full-length cDNAs encoding the preprocHH-A and preprocHH-B of the Norway lobster Nephrops norvegicus of 132 and 131 amino acid residues. The two cHHs differ in the preprohormone but not in the mature peptide sequence. The mature cHH was expressed in bacteria as GST fusion protein that, in bioassay, shows a hyperglycemic activity similar to that of native cHH present in an eyestalk extract.