Isolation and amino acid sequence of crustacean hyperglycemic hormone precursor-related peptides

The crustacean hyperglycemic hormone (CHH) is synthesized as part of a larger preprohormone in which the sequence of CHH is N-terminally flanked by a peptide for which the name CPRP (CHH precursor-related peptide) is proposed. Both CHH and CPRP are present in the sinus gland, the neurohemal organ of neurosecretory cells located in the eyestalk of decapod crustaceans. This paper describes the isolation and sequence analysis of CPRPs isolated from sinus glands of the crab Carcinus maenas, the crayfish Orconectes limosus and the lobster Homarus americanus. The published sequence of "peptide H" isolated from the land crab, Cardisoma carnifex, has now been recognized as a CPRP in this species. Sequence comparison reveals a high level of identity for the N-terminal region (residues 1-13) between all four peptides, while identity in the C-terminal domain is high between lobster and crayfish CPRP on the one hand, and between both crab species on the other. Conserved N-terminal residues include a putative monobasic processing site at position 11, which suggests that CPRP may be a biosynthetic intermediate from which a potentially bioactive decapeptide can be derived.