Tachibana K, Marquardt H, Yokoya S, Friesen H G
Department of Physiology, University of Manitoba, Winnipeg, Canada.
Mol Endocrinol. 1988 Oct;2(10):973-8. doi: 10.1210/mend-2-10-973.
We have reported that the secretion of at least 17 distinct peptides [including rat (rGH)] GH by cultured rat pituitary cells was stimulated by GH-releasing hormone and inhibited by somatostatin, when analyzed by two-dimensional polyacrylamide gel electrophoresis. Three of these peptides (no. 23, 24, and 25) were not rGH immunoreactive. In order to determine whether these three peptides are fragments, degradation products or posttranscriptionally modified forms of rGH, rGH and peptide no. 23 were characterized structurally. From partial peptide maps of rGH and peptide no. 23 by V8 protease or chymotrypsin, it appeared that these peptides were not related to each other. By N-terminal microsequencing of two-dimensional polyacrylamide gel electrophoresis purified peptide, we have obtained the sequence of 24 N-terminal amino acid residues of peptide no. 23. This sequence has no significant homology with rGH or any other reported protein sequence. Antiserum was generated against a synthetic oligopeptide corresponding to amino acid residues 3-24 of peptide no. 23. The antiserum cross-reacted with peptides no. 23, 24, and 25 upon Western blot analysis. These results indicate that peptide no. 23 has a novel structure unrelated to other pituitary hormones. Since its secretion is influenced by GH-releasing hormone and somatostatin, peptide no. 23 may represent a previously unrecognized structurally unique growth factor.
我们曾报道，通过二维聚丙烯酰胺凝胶电泳分析，培养的大鼠垂体细胞分泌的至少17种不同肽类（包括大鼠生长激素[rGH]）的生长激素受到生长激素释放激素的刺激，并受到生长抑素的抑制。其中三种肽（第23、24和25号）无rGH免疫反应性。为了确定这三种肽是否为rGH的片段、降解产物或转录后修饰形式，我们对rGH和第23号肽进行了结构表征。从rGH和第23号肽经V8蛋白酶或胰凝乳蛋白酶消化后的部分肽图谱来看，这些肽彼此无关。通过对二维聚丙烯酰胺凝胶电泳纯化的肽进行N端微量测序，我们获得了第23号肽24个N端氨基酸残基的序列。该序列与rGH或任何其他已报道的蛋白质序列均无显著同源性。针对与第23号肽氨基酸残基3 - 24对应的合成寡肽制备了抗血清。经蛋白质印迹分析，该抗血清与第23、24和25号肽发生交叉反应。这些结果表明，第23号肽具有与其他垂体激素无关的新结构。由于其分泌受生长激素释放激素和生长抑素的影响，第23号肽可能代表一种此前未被认识的结构独特的生长因子。
