Andrews P C, Ronner P
J Biol Chem. 1985 Apr 10;260(7):3910-4.
Both glucagon and the structurally similar glucagon-like peptide proteolytically derived from preproglucagon were purified from the endocrine pancreas of the channel catfish (Ictalurus punctata). This study represents the first report of the isolation of glucagon-like peptide from any source. Peptide sequences of glucagon-like peptide from other species have only been deduced from the cDNA sequences for preproglucagon. The sequence of the 34-residue glucagon-like peptide was found to be HADGTYTSDVSSYLQDQAAKDFITWLKSGQPKPE. Catfish glucagon-like peptide shares sequence identity at 26 of 31 residues with the putative glucagon-like peptide from anglerfish preproglucagon II. The mass of catfish glucagon-like peptide was found by fast atom bombardment-mass spectrometry to be 3785, identical with the value predicted by sequence analysis. This suggests that no post-translational modification occurs beyond proteolytic processing. The sequence of catfish glucagon was determined to be HSEGTFSNDYSKYLETRRAQDFVQWLM(N,S). Catfish glucagon exhibits a high degree of immunologic similarity with porcine glucagon by radioimmunoassay, whereas catfish glucagon-like peptide does not.
胰高血糖素和从胰高血糖素原前体蛋白经蛋白水解衍生而来的结构相似的胰高血糖素样肽，均从斑点叉尾鮰（Ictalurus punctata）的内分泌胰腺中纯化得到。本研究是关于从任何来源分离胰高血糖素样肽的首次报道。其他物种的胰高血糖素样肽的肽序列仅从胰高血糖素原前体蛋白的cDNA序列推导得出。发现34个残基的胰高血糖素样肽的序列为HADGTYTSDVSSYLQDQAAKDFITWLKSGQPKPE。斑点叉尾鮰的胰高血糖素样肽与安康鱼胰高血糖素原II推定的胰高血糖素样肽在31个残基中的26个残基处具有序列同一性。通过快原子轰击质谱法测得斑点叉尾鮰胰高血糖素样肽的质量为3785，与序列分析预测的值相同。这表明除了蛋白水解加工外，没有发生翻译后修饰。斑点叉尾鮰胰高血糖素的序列确定为HSEGTFSNDYSKYLETRRAQDFVQWLM(N,S)。通过放射免疫测定，斑点叉尾鮰胰高血糖素与猪胰高血糖素表现出高度的免疫相似性，而斑点叉尾鮰胰高血糖素样肽则不然。
