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

1988年，我们首次从人红细胞膜中发现了补体系统的调节因子MACIF，并于1989年成功克隆了其cDNA。应该注意的是，功能未知的抗原在1989年被命名为CD 59。目前已知CD 59与MACIF相同。当这个项目开始时，我正在研究MACIF（CD 59），如蛋白质表征和cDNA克隆。利用这一情况，我试图阐明MACIF（CD 59）的基因组结构。以MACIF cDNA为探针，从EMBL 3和Charon 4A等基因组文库中克隆了MACIF基因的阳性克隆，并将其亚克隆到M13大肠杆菌中。测定与cDNA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基因的外显子相似，但MACIF基因的内含子比Ly-6C基因的内含子长得多。目前，第一外显子的精确序列仍然未知。确定第一外显子的困难之一是由于第一和第二外显子被长度超过20 kb的内含子分开。

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.