Stoffers D A, Green C B, Eipper B A
Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205.
Proc Natl Acad Sci U S A. 1989 Jan;86(2):735-9. doi: 10.1073/pnas.86.2.735.
Peptidyl-glycine alpha-amidating monooxygenase (PAM; EC 1.14.17.3) catalyzes the conversion of a variety of glycine-extended peptides into biologically active alpha-amidated product peptides in a reaction dependent on copper, ascorbate, and molecular oxygen. We have isolated and sequenced cDNAs representing the two major classes of PAM mRNA in the adult rat heart atrium. The two types of cDNA, rPAM-1 and rPAM-2, are identical except for the deletion of a 315-base-pair segment within the protein coding region in rPAM-2, suggesting that rPAM-1 and rPAM-2 arise by alternative splicing. Northern analysis using a cDNA probe derived from within the 315-base-pair region deleted in rPAM-2 visualized the larger of the PAM mRNAs in adult rat atrium and not the smaller, indicating that the presence or absence of this 315-nucleotide segment is a major feature distinguishing the two size forms of PAM mRNA. The 105 amino acid segment that distinguishes the two forms of atrial PAM contains a consensus N-glycosylation site and a paired basic amino acid site of potential importance in endoproteolytic processing. Comparison of the nucleotide sequences of rat, frog, and bovine PAM cDNAs reveals an extremely well conserved segment in the 3' untranslated region. The high degree of conservation in amino acid sequence throughout the catalytic, intragranular, and cytoplasmic domains of rat atrium, bovine pituitary, and frog skin PAM suggests that both the catalytic and noncatalytic domains of the protein subserve important functions.
肽基甘氨酸α-酰胺化单加氧酶（PAM；EC 1.14.17.3）在依赖铜、抗坏血酸和分子氧的反应中，催化多种甘氨酸延伸肽转化为具有生物活性的α-酰胺化产物肽。我们已经分离并测序了代表成年大鼠心房中两种主要PAM mRNA类别的cDNA。两种类型的cDNA，即rPAM-1和rPAM-2，除了rPAM-2的蛋白质编码区域内缺失一个315个碱基对的片段外，其余部分相同，这表明rPAM-1和rPAM-2是通过可变剪接产生的。使用源自rPAM-2中缺失的315个碱基对区域内的cDNA探针进行的Northern分析，在成年大鼠心房中可视化了较大的PAM mRNA，而不是较小的，这表明该315个核苷酸片段的存在与否是区分两种大小形式的PAM mRNA的主要特征。区分两种心房PAM形式的105个氨基酸片段包含一个共有N-糖基化位点和一个在蛋白水解加工中可能具有重要意义的成对碱性氨基酸位点。大鼠、青蛙和牛PAM cDNA核苷酸序列的比较揭示了3'非翻译区域中一个极其保守的片段。大鼠心房、牛垂体和青蛙皮肤PAM的催化、颗粒内和细胞质结构域的氨基酸序列高度保守，这表明该蛋白质的催化和非催化结构域都发挥着重要功能。
