Primary structures of three fragments of proglucagon from the pancreatic islets of the daddy Sculpin (Cottus scorpius)

Abstract

A I K D F V A K L K S G K V represents the glucagon-like peptide at the COOH terminus of the precursor. The fast-atom bombardment mass spectra of the three peptides were consistent with the proposed structures and demonstrated that further posttranslational modifications of the peptides had not taken place. Sculpin glucagon is identical to anglerfish glucagon I1 but sculpin proglucagon(1-27) and glucagon-like peptide show stronger homology to the corresponding regions of anglerfish proglucagon I than to proglucagon 11. The structures of the peptides are suggestive of the action of trypsin-like and carboxypeptidase-B-like enzymes at the site of pairs of basic amino acid residues in proglucagon. The presence of a COOH-terminal lysyl group in proglucagon(1-27) may indicate, however, that the penultimate prolyl residue partially inhibits the action of the carboxypeptidase-B-like activity.The complete primary structure of proglucagon may be deduced from the nucleotide sequences of cDNA clones from the anglerfish [l], hamster [2], human [3], ox [4] and rat [5]. In the mammals, intervening sequences divide the protein-coding portion of single proglucagon genes into regions corresponding to the signal peptide and part of the NH,-tenninal peptide, the remainder of the NH2-terminal peptide and glucagon and two regions encoding peptides homologous to glucagon, termed glucagon-like peptide 1 (GLP-1) and glucagon-like peptide 2 (GLP-2) [3]. In the anglerfish, however, two non-allelic genes, encoding distinct proglucagons, have been characterized and both lack the region encoding GLP-2 Segregation of the endocrine pancreas of certain highly developed teleostean fishes into 'principal islets' or Brockmann bodies [6] has greatly facilitated the purification of peptides derived from the islet prohormones. Recent studies have led to the isolation of both glucagon and GLP from the anglerfish [7], catfish [8] and coho salmon [9]. In this study the amino acid sequences of the NH2-terminal region, glucagon and GLP region of sculpin proglucagon are compared with the corresponding sequences from other species in order to assess the relative evolutionary pressure acting upon the proglucagon molecule to conserve the structures of the different domains. This species was chosen as the principal islets of the sculpin, unlike the islets of many other teleostean fishes, are free from traversing strands of exocrine parenchyma [lo].[I].

Insights into the evolution of proglucagon‐derived peptides and receptors in fish and amphibians

“…Bony fish comprise the lobe‐finned and ray‐finned fishes, with the latter considered as the most heterogeneous and affluent vertebrate group based on species diversity and morphological complexity 26 . Multiple proglucagon gene copies are also found in several bony fish: Rainbow trout ( Oncorhynchus mykiss ), 27 anglerfish, 3 sculpin ( Cottus scorpius ), 28 eel ( Anguilla anguilla ), 29 and paddlefish ( Polyodon spathula ) 30 . By data mining of publically available genomes, two proglucagon copies were also predicted in the fugu ( Takifugu rubripes ), pufferfish ( Tetraodon nigroviridis ), medaka ( Orzyzias latipes ), and stickleback ( Gasterosteus aculeatus ) where one proglucagon encodes for all three derived peptides and the other encodes for glucagon and GLP‐1.…”

Metabolic response of teleost hepatocytes to glucagon-like peptide and glucagon

“…These peptides include glucagon, glucagon-like peptides (GLPs), glicentin and oxyntomodulin as well as additional processing products (Andrews & Ronner, 1985;Andrews, Hawke, Lee et al 1986;Orskov, Holst, Knuthsen et al 1986;Conlon, Falkmer & Thim, 1987;Pollock, Kimmel, Ebner et al 1988). While mammals possess one PPG gene, coencoding GLP-1, GLP-2 and glucagon, the situation in fishes is different.…”

Anatomic and molecular characterization of the endocrine pancreas of a teleostean fish: Atlantic wolffish (Anarhichas lupus)

“…The isolation and characterization of glucagon, insulin, somatostatin, and pancreatic polypeptide from islet tissues of several teleost fish were previously described (Cutfield et al 1986;Conlon et al 1987a;Conlon et al 1987b;Conlon et al 1986;Cutfield et al 1987;Cutfield and Cutfield 1993). The amino acid sequence and primary structure of teleost islet hormones slightly differs from their higher vertebrate counterparts (Nguyen et al 1995;Cutfield et al 1986;Falkmer and Olsson 1962;Conlon et al 1987a;Conlon et al 1987b;Conlon et al 1986;Cutfield et al 1987;Cutfield and Cutfield 1993). Islet amyloid polypeptide (IAPP) is a hormone of 37 amino acids that is co-secreted with insulin by the β cells of mammals (Westermark et al 2011).…”