Ouafik L, Giraud P, Salers P, Dutour A, Castanas E, Boudouresque F, Oliver C
Proc Natl Acad Sci U S A. 1987 Jan;84(1):261-4. doi: 10.1073/pnas.84.1.261.
A high peptidylglycine alpha-amidating mono-oxygenase (PAMase) activity has been measured in the pancreas of neonatal rats. A significant fraction of this activity is contained in the beta cells of the islets of Langerhans and is colocalized with thyrotropin-releasing hormone (TRH) and its precursor in secretory granules. The ontogenetic variation of PAMase activity in the pancrease parallels that of TRH concentrations, suggesting that this enzymatic activity is directly related to TRH biosynthesis. In addition, PAMase activity is able to generate TRH when incubated with less than Glu-His-Pro-Gly, a tetrapeptide present as a repetitive sequence in the TRH precursor. The perinatal evolution of the TRH precursor levels in the pancreas is similar to that of PAMase activity (unpublished results). Thus, the neonatal rat pancreas offers an endocrine model in which the levels of a neuropeptide precursor and an enzyme activity, involved in the posttranslational modification of this precursor, are similarly regulated. Our results suggest also that a fraction of PAMase activity may be produced outside of the beta cells and related to the biosynthesis of COOH-terminally amidated peptide(s) other than TRH. The ontogenetic changes in PAMase activity imply that the synthesis of this peptide(s) is high during the neonatal period, decreasing thereafter.
在新生大鼠的胰腺中检测到了高肽基甘氨酸α-酰胺化单加氧酶（PAMase）活性。该活性的很大一部分存在于胰岛的β细胞中，并与促甲状腺激素释放激素（TRH）及其前体共定位于分泌颗粒中。胰腺中PAMase活性的个体发生变化与TRH浓度的变化平行，这表明这种酶活性与TRH生物合成直接相关。此外，当与少于Glu-His-Pro-Gly（TRH前体中作为重复序列存在的一种四肽）一起孵育时，PAMase活性能够产生TRH。胰腺中TRH前体水平的围产期演变与PAMase活性的演变相似（未发表的结果）。因此，新生大鼠胰腺提供了一种内分泌模型，其中一种神经肽前体的水平和一种参与该前体翻译后修饰的酶活性受到类似的调节。我们的结果还表明，一部分PAMase活性可能在β细胞外产生，并且与TRH以外的C末端酰胺化肽的生物合成有关。PAMase活性的个体发生变化意味着这种肽在新生儿期的合成很高，此后逐渐降低。
