Talmadge K, Boorstein W R, Fiddes J C
DNA. 1983;2(4):281-9. doi: 10.1089/dna.1983.2.281.
We have used restriction enzyme analysis to sample similarities and differences among eight cloned genes, isolated from two independent libraries, which hybridize to a cDNA for the beta subunit of human chorionic gonadotropin (hCG). We find that one of the cloned genes encodes the beta-subunit of the closely related hormone, human luteinizing hormone (hLH). Using differential hybridization of human DNA with beta hCG- and beta hLH-specific probes, we show that there are seven beta hCG genes but only a single beta hLH gene in the human genome. This single beta hLH gene is linked to at least three beta hCG genes. Our restriction analysis reveals that the seven beta hCG genes are extremely similar but not identical, and that there are no obvious structural rearrangements to indicate which, if any, are pseudogenes. These data also reveal that the beta hLH gene is far more homologous to the seven beta hCG genes than the beta hCG:beta hLH protein sequence homology of 82% might predict. We propose that the beta hCG gene arose by a duplication of an ancestral beta hLH gene and that, once the beta hCG function was established, the ancestral beta hCG gene itself duplicated and rearranged, creating the present organization of multiple beta hCG genes.
我们利用限制性内切酶分析对从两个独立文库中分离出的八个克隆基因进行了相似性和差异性分析，这些基因与人类绒毛膜促性腺激素（hCG）β亚基的cDNA杂交。我们发现其中一个克隆基因编码密切相关的激素——人促黄体生成素（hLH）的β亚基。通过用人DNA与β hCG和β hLH特异性探针进行差异杂交，我们表明人类基因组中有七个β hCG基因，但只有一个β hLH基因。这个单一的β hLH基因与至少三个β hCG基因相连。我们的限制性分析表明，这七个β hCG基因极其相似但并不完全相同，并且没有明显的结构重排来表明哪些（如果有的话）是假基因。这些数据还表明，β hLH基因与这七个β hCG基因的同源性远比β hCG与β hLH蛋白质序列82%的同源性所预测的要高。我们提出β hCG基因起源于一个祖先β hLH基因的复制，并且一旦β hCG功能确立，祖先β hCG基因自身进行了复制和重排，形成了目前多个β hCG基因的组织形式。
