Purification and sequencing of molluscan insulin-related peptide II from the neuroendocrine light green cells in Lymnaea stagnalis.
The growth-controlling neuroendocrine light green cells of the freshwater snail, Lymnaea stagnalis, express a family of genes encoding structurally related, yet distinct, molluscan insulin-related peptides (MIPs). In the present study one of these peptides, MIP II, has been isolated and structurally identified. MIP II is a heterodimer of A and B chains connected by disulfide bonds. Both chains are N-terminally blocked with pyroglutamate. After cleaving of the A and B chains and deblocking with pyroglutamate amino-peptidase their sequences have been determined as: A chain: pQRTTNLVCECCFNYCTPDVVRKYCY and B chain: pQSSCSLSSRPHPRGICGSNLAGFRAFICSNQNSPS. In comparison with the MIP II sequence based on complementary DNA studies, it is clear that the two C-terminal amino acid residues of the B chain are posttranslationally removed. In addition, the glutamic acid residue in A chain was recovered in very low yields during Edman degradation, suggesting that the residue may be posttranslationally modified.
Faculty of Biology, Vrije Universiteit, Amsterdam, The Netherlands.
K W
KW
Li
W P
WP
Geraerts
J
J
Joosse
D000595:Amino Acid Sequence; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D008195:Lymnaea / Q000166:cytology / Q000235:genetics / Q000502:physiology*; D046911:Macromolecular Substances; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D005810:Multigene Family; D009424:Nervous System Physiological Phenomena; D009479:Neuropeptides / Q000235:genetics / Q000302:isolation & purification*; D010449:Peptide Mapping; D011498:Protein Precursors / Q000235:genetics; D011751:Pyroglutamyl-Peptidase I
D046911:Macromolecular Substances; D009479:Neuropeptides; D011498:Protein Precursors; C063879:insulin-related neuropeptide; D011751:Pyroglutamyl-Peptidase I