Mortin M A, Kim W J, Huang J
Department of Biochemistry and Molecular Biology, Harvard University, Cambridge, Massachusetts 02138.
Genetics. 1988 Aug;119(4):863-73. doi: 10.1093/genetics/119.4.863.
The RpII215 locus encodes the large subunit of RNA polymerase II (polII). Three of 22 RpII215 alleles cause a synergistic enhancement of the mutant phenotype elicited by mutations in the Ultrabithorax (Ubx) locus. We have recovered and analyzed three new mutations that suppress this enhancement. All three mutations map to the RpII215 locus. In addition to suppressing the Ubx enhancement of other RpII215 alleles, two of the new mutations, JH1 and WJK2, themselves enhance Ubx. RpII215 alleles can be placed into three classes based on their ability to enhance Ubx. Class I alleles, including Ubl, C4, C11, JH1, and WJK2, enhance Ubx when heterozygous with class II alleles, which include wild-type RpII215. Class III alleles, which include amorphic alleles, do not enhance Ubx. The third new mutation, WJK1, is a conditional amorphic allele, which behaves like a class III allele at 29 degrees but like a class II allele at 19 degrees. Another mutant phenotype is caused by certain RpII215 alleles, including all class I alleles. This phenotype is a synergistic enhancement of a mutant phenotype elicited by mutations at the Delta (Dl) locus. Unlike the enhancement of Ubx, the enhancement of Dl is not dependent upon antagonistic interactions between different classes of RpII215 alleles.
RpII215基因座编码RNA聚合酶II（polII）的大亚基。22个RpII215等位基因中有3个会协同增强由超双胸（Ubx）基因座突变引发的突变表型。我们已经获得并分析了三个抑制这种增强作用的新突变。所有这三个突变都定位于RpII215基因座。除了抑制其他RpII215等位基因的Ubx增强作用外，其中两个新突变JH1和WJK2自身也增强Ubx。RpII215等位基因可根据其增强Ubx的能力分为三类。I类等位基因，包括Ubl、C4、C11、JH1和WJK2，与II类等位基因（包括野生型RpII215）杂合时会增强Ubx。III类等位基因，包括无义等位基因，不会增强Ubx。第三个新突变WJK1是一个条件性无义等位基因，在29摄氏度时表现得像III类等位基因，但在19摄氏度时表现得像II类等位基因。另一种突变表型是由某些RpII215等位基因引起的，包括所有I类等位基因。这种表型是由Delta（Dl）基因座突变引发的突变表型的协同增强。与Ubx的增强作用不同，Dl的增强不依赖于不同类别的RpII215等位基因之间的拮抗相互作用。
