title: Primary structure of the precursor for the anthozoan neuropeptide antho-RFamide from Renilla köllikeri: evidence for unusual processing enzymes.
abstract: Neuropeptides containing the C-terminal sequence Arg-Phe-NH2 are an important group of hormones mediating or modulating neuronal communication. Arg-Phe-NH2 peptides are abundant in evolutionarily "old" nervous systems such as those of coelenterates, the lowest animal group having a nervous system. Here, we have cloned the precursor protein for the anthozoan neuropeptide Antho-RFamide (< Glu-Gly-Arg-Phe-NH2) from the sea pansy Renilla köllikeri. This precursor contains 36 copies of immature Antho-RFamide (Gln-Gly-Arg-Phe-Gly) and two additional putative neuropeptide sequences, which are regularly distributed over the precursor protein. Of the 36 Antho-RFamide sequences, 29 copies are separated by the five amino acid spacer sequence Arg-Glu/Gly-Asn/Ser/Asp-Glu/Lys-Glu. This implicates processing at single Arg and single Glu residues. Endoproteolytic cleavage at the C-terminal side of paired or single basic residues is a well known initial step in the maturation of precursor proteins. Cleavage at the C-terminal side of acidic residues, however, is unusual and must be catalyzed by a new type of processing enzyme. This processing enzyme is most likely to be an endoprotease, because the simplest way to generate Antho-RFamide is by endoproteolytic cleavage at the C-terminal side of Glu residues. The enzyme could also be an aminopeptidase, but in this case other proteases must be involved. As a possible alternative, one single "unspecific" aminopeptidase could cleave at Glu, Asp, Gly, Asn, Ser, and possibly also at other residues, and thus liberate all Antho-RFamide sequences. The processing of one precursor molecule probably yields 38 neuropeptides.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Centre for Molecular Neurobiology (ZMNH), University of Hamburg, F.R.G.
authors.forename: R K
authors.initials: RK
authors.lastname: Reinscheid
authors.forename: C J
authors.initials: CJ
authors.lastname: Grimmelikhuijzen
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003063:Cnidaria / Q000201:enzymology / Q000378:metabolism*; D018076:DNA, Complementary / Q000235:genetics / Q000302:isolation & purification; D015335:Molecular Probes / Q000235:genetics; D008969:Molecular Sequence Data; D009479:Neuropeptides / Q000235:genetics* / Q000378:metabolism; D011498:Protein Precursors / Q000235:genetics* / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D011761:Pyrrolidonecarboxylic Acid / Q000031:analogs & derivatives
chemical_list: D018076:DNA, Complementary; D015335:Molecular Probes; D009479:Neuropeptides; D011498:Protein Precursors; C060288:4-pyroglutamyl-glycyl-arginyl-phenylalaninamide; D011761:Pyrrolidonecarboxylic Acid