Devriendt K, Zhang J, van Leuven F, van den Berghe H, Cassiman J J, Marynen P
Center for Human Genetics, University of Leuven, Belgium.
Gene. 1989 Sep 30;81(2):325-34. doi: 10.1016/0378-1119(89)90193-5.
The characterization of two alpha 2-macroglobulin (alpha 2M)-related genomic clones, isolated from two human genomic libraries by use of alpha 2M cDNA [Kan et al., Proc. Natl. Acad. Sci. USA 82 (1985) 2282-2286] as a probe, is reported. Sequence comparison of the clone EPZP6 with the human alpha 2M cDNA revealed the presence of five exons with the proper splice signals. Alignment of the corresponding amino acid (aa) sequence of these exons with the published partial pregnancy-zone protein (PZP) aa sequence (Sottrup-Jensen et al., Proc. Natl. Acad. Sci. USA 81 (1984) 7353-7357] showed a perfect match, thereby identifying EPZP6 as a PZP genomic clone. The clone MPAM16 showed a considerable degree of sequence conservation when compared to the human alpha 2M cDNA sequence, and several putative exons were identified. However, a frame-shift mutation leading to a premature stop codon was found in the coding sequence, classifying this gene as an alpha 2M pseudogene. Human alpha 2M, PZP and the related pseudogene were mapped to the human chromosome 12p12-13, with the help of gene-specific probes and in situ hybridization. This result was confirmed in Southern-blot experiments with DNA from a human-Ltk- mouse somatic-cell hybrid containing only a human isochromosome 12p in a mouse background.
报道了利用α2M cDNA[Kan等人，《美国国家科学院院刊》82(1985)2282 - 2286]作为探针，从两个人类基因组文库中分离出的两个与α2巨球蛋白(α2M)相关的基因组克隆的特征。将克隆EPZP6与人类α2M cDNA进行序列比较，发现存在五个具有正确剪接信号的外显子。将这些外显子的相应氨基酸(aa)序列与已发表的部分妊娠区蛋白(PZP)aa序列[Sottrup-Jensen等人，《美国国家科学院院刊》81(1984)7353 - 7357]进行比对，结果显示完全匹配，从而将EPZP6鉴定为PZP基因组克隆。与人类α2M cDNA序列相比，克隆MPAM16显示出相当程度的序列保守性，并鉴定出几个推定的外显子。然而，在编码序列中发现了导致提前终止密码子的移码突变，将该基因归类为α2M假基因。借助基因特异性探针和原位杂交技术，将人类α2M、PZP和相关假基因定位到人类染色体12p12 - 13上。在来自仅含有在小鼠背景中的人类12号等臂染色体p的人 - Ltk - 小鼠体细胞杂种的DNA的Southern印迹实验中证实了这一结果。
