Differential mechanisms for the N-acetylation of alpha-melanocyte-stimulating hormone and beta-endorphin in the intermediate pituitary of the frog, Xenopus laevis.
Differential mechanisms for the N-acetylation of alpha-melanocyte-stimulating hormone and beta-endorphin in the intermediate pituitary of the frog, Xenopus laevis.
复制标题
非洲爪蟾垂体中叶中 α-黑素细胞刺激激素和 β-内啡肽 N-乙酰化的不同机制。
DOI：
10.1159/000125697
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发表时间：
1991
影响因子：
4.1
通讯作者：
Lopez,K
中科院分区：
文献类型：
--
作者：
Dores,RM;Steveson,TC;Lopez,K
对非洲爪蟾（Xenopus laevis）垂体的免疫组织化学分析表明，α-黑素细胞刺激激素（MSH）相关免疫反应和N-乙酰-β-内啡肽相关免疫反应共定位于垂体中间层细胞。为了确定免疫反应性N-乙酰化β-内啡肽是否与免疫反应性α-MSH平行释放，将中间垂体在L-15培养基中孵育24 h。分别通过凝胶过滤色谱法、反相高效液相色谱法和阳离子交换色谱法的组合对来自每次孵育的中间垂体的培养基和酸提取物进行分级。在中间垂体提取物中，α-MSH的主要形式具有色谱特性，对应于非乙酰化α-MSH（ACTH）（1-13）酰胺;而β-内啡肽的主要形式具有1.2 kDa的表观分子量，并且是N-乙酰化的。β-内啡肽和ACTH（1-13）酰胺的1.2-kDa形式以等摩尔量存在。对媒介的分析表明，两种最终产品是并行发布的。然而，如文献中所报道的，在分泌期间ACTH（1-13）酰胺的N-乙酰化显著增加。β-内啡肽在分泌过程中没有进一步加工。总的来说，这些观察结果表明，在中间垂体的X。α-MSH和β-endorphin的N-乙酰化反应有不同的机理。
Immunohistochemical analysis of the pituitary ofXenopus laevisrevealed the colocalization of α-melanocyte-stimulating-hormone (MSH)-related immunoreactivity and N-acetyl-β-endorphin-related immunoreactivity in the cells of the intermediate pituitary. In order to determine whether the immunoreactive N-acetylated β-endorphin is released in parallel with the immunoreactive α-MSH, intermediate pituitaries were incubated in L-15 medium for 24 h. The medium and an acid extract of the intermediate pituitaries from each incubation were separately fractionated by a combination of gel filtration chromatography, reverse-phase high-performance liquid chromatography, and cation exchange chromatography. In the intermediate pituitary extract, the major form of α-MSH had chromatographic properties which corresponded to nonacetylated α-MSH (ACTH)(1–13)amide; whereas the major form of β-endorphin had an apparent molecular weight of 1.2 kDa and was N-acetylated. The 1.2-kDa form of β-endorphin and ACTH(1–13)amide were present in equimolar amounts. Analysis of the medium indicated that both end products were released in parallel. However, as reported in the literature, there was a significant increase in the N-acetylation of ACTH(1–13)amide during secretion. There was no further processing of β-endorphin during secretion. Collectively, these observations indicate that in the intermediate pituitary ofX. laevisthere are separate mechanisms for the N-acetylation of α-MSH and β-endor-phin.