Platteborze P L, Hobart M J, Sodetz J M
Department of Chemistry and Biochemistry, University of South Carolina, Columbia 29208, USA.
Hum Genet. 1996 Oct;98(4):443-6. doi: 10.1007/s004390050236.
Human C8 is one of five components (C5b, C6, C7, C8, C9) of the cytolytic C5b-9 complex of complement. It consists of three nonidentical subunits (C8 alpha, C8 beta, C8 gamma), which are encoded in separate genes. Genetic linkage and chromosomal localization studies previously established that C8 alpha and C8 beta are closely linked on chromosome 1p32. In this study, clones with inserts containing genes for both C8 alpha and C8 beta were isolated from a yeast artificial chromosome (YAC) human genomic DNA library and characterized in an effort to determine intergenic distance and orientation. One clone with a approximately 330-kb insert yielded restriction digest patterns for C8 alpha and C8 beta that agreed with those obtained previously from digests of human genomic DNA, thereby confirming the presence of intact copies of both genes. A second clone with a approximately 280-kb insert yielded similar results; however, it was truncated at the 5' end of the C8 alpha gene. Restriction digests of both clones were subjected to PFGE and Southern blot analysis using probes specific for the terminal exons of C8 alpha (exons 1 and 11) and C8 beta (exons 1 and 12). Results indicate the genes are physically linked (< 23 kb) and in a 3'-3' orientation. This is the same orientation as the ancestrally related C6 and C7 genes, which are also physically linked on chromosome 5p13.
人C8是补体溶细胞性C5b - 9复合物的五个组分（C5b、C6、C7、C8、C9）之一。它由三个不同的亚基（C8α、C8β、C8γ）组成，这些亚基由不同的基因编码。先前的遗传连锁和染色体定位研究表明，C8α和C8β在1号染色体p32区域紧密连锁。在本研究中，从酵母人工染色体（YAC）人类基因组DNA文库中分离出含有C8α和C8β基因插入片段的克隆，并对其进行表征，以确定基因间距离和方向。一个插入片段约为330 kb的克隆产生的C8α和C8β的限制性消化图谱与先前从人类基因组DNA消化产物中获得的图谱一致，从而证实了两个基因完整拷贝的存在。另一个插入片段约为280 kb的克隆也得到了类似的结果；然而，它在C8α基因的5'端被截断。对两个克隆的限制性消化产物进行脉冲场凝胶电泳（PFGE）和Southern印迹分析，使用针对C8α（外显子1和11）和C8β（外显子1和12）末端外显子的特异性探针。结果表明，这两个基因在物理上是连锁的（< 23 kb），且呈3'-3'方向。这与在5号染色体p13区域也在物理上连锁的祖先相关基因C6和C7的方向相同。
