Eder P S, Kekuda R, Stolc V, Altman S
Department of Biology, Yale University, New Haven, CT 06520, USA.
Proc Natl Acad Sci U S A. 1997 Feb 18;94(4):1101-6. doi: 10.1073/pnas.94.4.1101.
Human RNase P has been purified more than 2000-fold from HeLa cells. In addition to the RNA component, H1 RNA, polypeptides of molecular masses 14, 20, 25, 30, 38, and 40 kDa copurify with the enzyme activity. Sera from two different patients with the autoimmune disease scleroderma were used to immunodeplete human RNase P activity. These same sera cross-reacted on immunoblots with two of the copurifying polypeptides, p30 and p38, whereas an autoimmune serum that does not immunodeplete RNase P activity did not react with these proteins. Peptide fragments derived from purified p30 and p38 facilitated the molecular cloning and sequencing of cDNAs coding for these two polypeptides, which are now designated as Rpp30 and Rpp38, respectively. RPP38 cDNA encodes a polypeptide that may be identical to a previously identified antigen of approximately 40 kDa, which is immunoprecipitated by Th and To autoimmune antisera, and that has been implicated as a protein subunit of human RNase P by virtue of its ability to bind to H1 RNA in vitro. The second autoimmune antigen, Rpp30, as such, has not been described previously.
人核糖核酸酶P已从人宫颈癌细胞系HeLa细胞中纯化了2000多倍。除RNA成分H1 RNA外，分子量为14、20、25、30、38和40 kDa的多肽与该酶活性共纯化。使用来自两名患有自身免疫性疾病硬皮病的不同患者的血清免疫去除人核糖核酸酶P活性。这些血清在免疫印迹上与两种共纯化的多肽p30和p38发生交叉反应，而一种不能免疫去除核糖核酸酶P活性的自身免疫血清则不与这些蛋白质发生反应。从纯化的p30和p38获得的肽片段有助于对编码这两种多肽的cDNA进行分子克隆和测序，这两种多肽现在分别命名为Rpp30和Rpp38。RPP38 cDNA编码的一种多肽可能与先前鉴定的约40 kDa的抗原相同，该抗原可被Th和To自身免疫抗血清免疫沉淀，并且由于其在体外与H1 RNA结合的能力而被认为是人核糖核酸酶P的一个蛋白质亚基。第二种自身免疫抗原Rpp30此前尚未被描述过。
