Eipper B A, Green C B, Mains R E
Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Md.
J Natl Cancer Inst Monogr. 1992(13):163-8.
The biosynthesis of many peptides thought to have autocrine or paracrine effects on cell growth requires a series of enzymatic steps. The level of expression of two of these posttranslational processing enzymes was compared in several endocrine and non-neuroendocrine cell lines. Peptidylglycine alpha-amidating monooxygenase (PAM; EC 1.14.17.3) is a bifunctional copper- and ascorbate-dependent enzyme essential in the formation of alpha-amidated peptides. Carboxypeptidase H (CPH; EC 3.4.17.10) removes basic residues from the carboxyterminus of the products of endoproteolytic cleavage of prohormones and is generally essential in the formation of substrates for PAM. PAM messenger RNA (mRNA) and activity were detectable in both endocrine (AtT-20, GH3) and non-neuroendocrine (L, 3T3, COS, BRL, C127) cells. Except for BRL cells, CPH mRNA and enzymatic activity were detectable in all the cell lines. BRL cells contained no detectable CPH mRNA and had a different carboxypeptidase B-like activity. Thus, expression of secretory granule-associated processing enzymes is not limited to cells of a classic neuroendocrine phenotype.
许多被认为对细胞生长具有自分泌或旁分泌作用的肽的生物合成需要一系列酶促步骤。在几种内分泌和非神经内分泌细胞系中比较了这两种翻译后加工酶的表达水平。肽基甘氨酸α-酰胺化单加氧酶（PAM；EC 1.14.17.3）是一种双功能的铜和抗坏血酸依赖性酶，对α-酰胺化肽的形成至关重要。羧肽酶H（CPH；EC 3.4.17.10）从激素原内蛋白水解裂解产物的羧基末端去除碱性残基，通常对PAM底物的形成至关重要。在内分泌细胞（AtT-20、GH3）和非神经内分泌细胞（L、3T3、COS、BRL、C127）中均检测到PAM信使核糖核酸（mRNA）和活性。除BRL细胞外，在所有细胞系中均检测到CPH mRNA和酶活性。BRL细胞未检测到CPH mRNA，且具有不同的羧肽酶B样活性。因此，分泌颗粒相关加工酶的表达不限于经典神经内分泌表型的细胞。
