Search of a gene family containing MACIF, a regulatory membrane protein of complement system

1988年，我们首次发现了人红细胞膜补体系统的调节因子MACIF，并在的研究中成功地克隆了它。应该指出的是，一种功能未知的抗原在1989年被命名为CD59。CD59现在已知与Macif相同。当这个项目开始的时候，我正在进行Macif(CD59)的研究，比如蛋白质特性和cDNA克隆。利用这种情况，我试图阐明Macif(CD59)的基因组结构。以MACIFcDNA为探针，从EMBL3和Charon 4A等基因组文库中克隆了几个阳性克隆，并将其亚克隆到M13噬菌体中。测定了与该基因杂交的克隆的核苷酸序列。结果表明，MACIF基因组由4个外显子组成。第一个外显子编码5‘-侧翼序列，第二个外显子编码大部分信号序列，第三个外显子编码MACIF的N端31个残基，第四个外显子编码除3’-侧翼序列外的其余残基。这些外显子与Ly-6C基因相似，但Macif基因的内含子比Ly-6C基因的内含子长得多。目前，第一个外显子的精确序列仍不清楚。确定第一外显子的困难之一来自于第一外显子和第二外显子被长度超过20kb的内含子分开的事实。

In 1988 we first found a regulatory factor, MACIF, of complement system from human erythrocyte membranes, and succeeded in its cDNA cloning in 1989. It should be noted that an antigen whose function was unknown was named CD59 in 1989. CD59 is now known to be identical with MACIF. When this project started, I was running the top on the study of MACIF(CD59) such as protein characterization and cDNA cloning. Taking the advantage of the situation, I tried to elucidate the genomic structure of MACIF(CD59). I also expected that MACIF gene made a cluster with its homologous genes, because the genes of mouse Ly-6 antigens, a homologue of MACIF, are known to make a cluster on mouse genome.Several positive clones were cloned from genomic libraries such as EMBL3 and Charon 4A by using MACIFcDNA as a probe, and subcloned into M13 phages. The nucleotide sequences of the clones hybridized with the cDNA were determined. The results indicated that MACIF genome was made from four exons. The first exon encoded 5'-flanking sequene, the second one encoded a large part of signal sequence, the third one encoded N-terminal 31 residues of MACIF, and the fourth one encoded the remaining residues besides 3'-flanking sequence. Those exons are similar to those of Ly-6C gene, but the introns of MACIF gene are much longer than those of Ly-6C gene. Presently the precise sequence of the first exon is still unknown. One of the difficulties for determination of the first exon is derived from the fact that the first and second exons are divided with an intron of more than 20 kb length.