Donelson J E, Young J R, Dorfman D, Majiwa P A, Williams R O
Nucleic Acids Res. 1982 Nov 11;10(21):6581-95. doi: 10.1093/nar/10.21.6581.
The cDNA sequence for the variable surface glycoprotein (VSG) expressed in Trypanosoma brucei clone ILtat 1.4 (called clone D for brevity) hybridizes strongly to three regions in trypanosome genomic DNA. These three regions were extensively characterized by Southern hybridization analyses, genomic DNA cloning and DNA sequence determinations. All three regions occur in the genomes of all trypanosome clones of the ILTAR 1 repertoire regardless of whether or not VSG D was being expressed. Extensive (clone dependent) DNA rearrangements and a (clone independent) double strand DNA break were found distal to the 3'-end of the VSG D coding sequence of one of the regions. VSG D mRNA is most likely synthesized from this region, but a recombinant DNA clone of the VSG coding sequence could not be obtained for confirmation. Recombinant clones of the other two regions were obtained. DNA sequence analyses revealed that their coding sequences differ from each other by 17%. They differ from the ILtat 1.4 cDNA sequence by 4% in one case, and 13% in the other. By analogy with another VSG gene system, one of these two regions may have originally given rise to the third region from which the mRNA is probably transcribed.
在布氏锥虫克隆ILtat 1.4（简称为克隆D）中表达的可变表面糖蛋白（VSG）的cDNA序列与锥虫基因组DNA中的三个区域强烈杂交。通过Southern杂交分析、基因组DNA克隆和DNA序列测定对这三个区域进行了广泛的表征。所有三个区域都存在于ILTAR 1库的所有锥虫克隆的基因组中，无论是否表达VSG D。在其中一个区域的VSG D编码序列的3'端远端发现了广泛的（克隆依赖性）DNA重排和一个（克隆非依赖性）双链DNA断裂。VSG D mRNA很可能是从该区域合成的，但无法获得VSG编码序列的重组DNA克隆进行确认。获得了其他两个区域的重组克隆。DNA序列分析表明，它们的编码序列彼此相差17%。在一种情况下，它们与ILtat 1.4 cDNA序列相差4%，在另一种情况下相差13%。与另一个VSG基因系统类似，这两个区域中的一个可能最初产生了第三个区域，mRNA可能从该区域转录。
