Vik D P, Muñoz-Cánoves P, Kozono H, Martin L G, Tack B F, Chaplin D D
Department of Immunology, Research Institute of Scripps Clinic, La Jolla, California 92037.
J Biol Chem. 1990 Feb 25;265(6):3193-201.
Mouse liver RNA analyzed by Northern blotting with a full-length complement factor H cDNA probe demonstrates the 4.4-kilobase (kb) H mRNA as well as three additional hybridizing species of 3.5, 2.8, and 1.8 kb, respectively. Further characterization of these alternative transcripts was pursued by isolation of additional cDNAs from a liver library using a full-length H probe. Twelve clones homologous to but distinct from H were isolated, analyzed by restriction mapping, and divided into four classes, A, B, C, and D, based on their sequences. Clones from classes A, B, and C all contained nearly identical 5'-untranslated regions and leader sequences that differed from H at more than 50% of their nucleotide positions. The 5'-untranslated and leader sequences of the class D clone were unrelated to the corresponding regions of H or the class A, B, or C clones. The remaining portions of the H-related cDNAs were made up of short consensus repeats, 7 in class A, 4 in class B, 13 in class C, and 5 in class D. To determine the relationship between the H-related transcripts and the cDNA clones, Northern blots of liver RNA were analyzed by hybridization with two probes, one specific for the class D cDNA and the other reacting specifically with the class A, B, and C cDNAs. The class A/B/C probe detected transcripts of 3.5, 2.8, and 1.8 kb in liver RNA, and the class D probe hybridized to a distinct 1.8-kb message. Additionally, a cosmid genomic library was screened with H cDNA, and nine H-related clones were isolated. They spanned a region of approximately 120 kb, defining at least two discrete H-related gene loci. These results identify new members of the super-family of C3b/C4b binding protein genes.
用全长补体因子H cDNA探针通过Northern印迹分析小鼠肝脏RNA，结果显示有4.4千碱基（kb）的H mRNA以及另外三种分别为3.5、2.8和1.8 kb的杂交条带。通过使用全长H探针从肝脏文库中分离更多cDNA，对这些可变转录本进行了进一步表征。分离出了12个与H同源但不同的克隆，通过限制性图谱分析，并根据其序列分为A、B、C和D四类。A、B和C类克隆均含有几乎相同的5'非翻译区和前导序列，这些序列在超过50%的核苷酸位置上与H不同。D类克隆的5'非翻译区和前导序列与H或A、B或C类克隆的相应区域无关。H相关cDNA的其余部分由短共有重复序列组成，A类有7个，B类有4个，C类有13个，D类有5个。为了确定H相关转录本与cDNA克隆之间的关系，用两种探针杂交分析肝脏RNA的Northern印迹，一种对D类cDNA特异，另一种与A、B和C类cDNA特异反应。A/B/C类探针在肝脏RNA中检测到3.5、2.8和1.8 kb的转录本，D类探针与一条不同的1.8 kb条带杂交。此外，用H cDNA筛选黏粒基因组文库，分离出9个H相关克隆。它们跨越了大约120 kb的区域，确定了至少两个离散的H相关基因座。这些结果鉴定出了C3b/C4b结合蛋白基因超家族的新成员。
