Biosynthesis of glucagon.
Biosynthesis of glucagon.
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胰高血糖素的生物合成。
DOI：
10.1016/s0026-0495(76)80137-0
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发表时间：
1976
期刊：
影响因子：
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通讯作者：
B. D. Noe
中科院分区：
文献类型：
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作者：
B. D. Noe
虽然我们已经研究了包括人类在内的几种动物胰岛组织中胰高血糖素的生物合成，但本文讨论的结果将仅限于使用琵琶鱼胰岛进行研究所获得的数据。最近的研究中，利用过氧化物酶-二氨基联苯胺技术已导致生长抑素，胰岛素，胰高血糖素细胞在琵琶鱼胰岛的免疫组织化学定位。从对三种激素中的每一种特异性反应的连续连续切片制备的透明照相机绘图表明，δ细胞占胰岛体积的约40%，β细胞占35%-40%，α细胞占20%。尽管这三种细胞类型彼此紧密并列，但免疫特异性的重叠很少。为了研究胰高血糖素的生物合成，放射性色氨酸被选择性地掺入胰高血糖素和胰高血糖素相关肽中。绵羊和猪的生长抑素都有一个色氨酸残基。然而，我们没有观察到任何色氨酸标记物在预期十四肽会粘附在经色氨酸标记的琵琶鱼胰岛组织提取物的凝胶过滤上的位置洗脱。生长抑素可能是TCA可溶性或酸乙醇-乙酸不溶性的。因此，认为用该提取方法获得的胰岛提取物主要含有胰岛素相关肽和胰高血糖素相关肽。这一假设得到了用3 H-色氨酸和14 C-异亮氨酸（对胰岛素原和胰岛素特异;哺乳动物生长抑素和琵琶鱼胰高血糖素缺乏异亮氨酸）标记的胰岛组织提取物凝胶过滤后观察到的洗脱模式的支持。在连续和脉冲追踪孵育后，异亮氨酸仅掺入胰岛素原和胰岛素中。色氨酸被掺入到至少四种不同分子大小的肽中，所有这些肽都具有胰高血糖素免疫反应性，如通过Unger 30 K抗血清测定的。在琵琶鱼胰岛的酸性乙醇-乙酸提取物中发现的最大的含胰高血糖素的免疫反应性肽具有接近12，000道尔顿的分子大小。它是短脉冲孵育后主要的Dahan标记肽，但似乎迅速转化为分子大小接近9000道尔顿的肽。4聚丙烯酰胺凝胶电泳（PAGE）、离子交换层析和等电聚焦电泳结果表明，分子量为-12，000和-9，000的胰高血糖素相关肽均为酸性。
A LTHOUGH we have studied glucagon biosynthesis in pancreatic islet tissue from several species, including humans, the results discussed in this paper w'ill be confined to data obtained from studies using anglerfish islet. Recent studies in which the peroxidase-diaminobenzidine technique was utilized have resulted in the immunohistochemical localization of somatostatin-, insulin-, and glucagon-containing cells in anglerfish islet. Camera lucida drawings prepared from sequential serial sections reacted specifically for each of the three hormones indicate that delta cells comprise-40~ of the islet volume, beta cells-35%-40%, and alpha cells-20%. Although all three cell types are in close apposition to each other, very little overlap in immunospecificity was observed.For studying glucagon biosynthesis, radioactive tryptophan is incorporated selectively into glucagon and glucagon-related peptides. Both ovine and porcine somatostatin possess one tryptophan residue. 1'2 However, we fail to observe any tryptophan label eluting in a position where a tetradecapeptide would be expected to elute on gel filtration of tryptophan-labeled anglerfish islet tissue extracts. It is probable that somatostatin is TCA soluble or acid ethanol-acetic acid insoluble. Islet extracts obtained with this extraction procedure are thus thought to contain primarily insulin-related and glucagon-related peptides. This assumption is supported by the elution patterns observed after gel filtration of extracts of islet tissue labeled with 3H-tryptophan and 14C-isoleucine (specific for proinsulin and insulin; mammalian somatostatin and anglerfish glucagon lack isoleucine) J 3 After both continuous and pulse-chase incubations, isoleucine is incorporated into proinsulin and insulin only. Tryptophan becomes incorporated into at least four peptides of varying molecular size, all of which possess glucagon immunoreactivity as determined by Unger 30K antiserum. The largest tryptophan-containing glucagon immunoreactive peptide found in acid ethanol-acetic acid extracts of anglerfish islet has a molecular size near 12,000 daltons. It is the predominant tryptophan-labeled peptide after short pulse incubations but appears to be converted rapidly to a peptide having a molecular size near 9000 daltons. 4 Results from polyacrylamide gel electrophoresis (PAGE), ion exchange chromatography and isoelectric focusing indicate that both the-12,000 molecular weight and-9000 molecular weight glucagon-related peptides are acidic.