Reynolds N, MacNeill S A
Institute of Cell and Molecular Biology, University of Edinburgh, Michael Swann Building, King's Buildings, Mayfield Road, Edinburgh EH9 3JR, UK.
Gene. 1999 Apr 1;230(1):15-22. doi: 10.1016/s0378-1119(99)00058-x.
DNA polymerase delta (Pol delta), which plays keys roles in DNA replication, repair and recombination in eukaryotic cells, comprises at least two essential subunits - a large catalytic subunit (PolD1) possessing both DNA polymerase and 3'-5' exonuclease activities, and a smaller subunit (PolD2) whose function is not yet clear. Here we describe the cloning and sequencing of a Xenopus cDNA encoding a homologue of the PolD2 subunit. This protein (designated XlCdc1) is 69% identical to the human PolD2 protein and 34% identical to fission yeast Cdc1. Alignment of PolD2 protein sequences across ten eukaryotic species identifies 36 invariant amino-acid positions. These 36 residues are located within ten conserved regions (designated I-X) likely to have key functional roles. Consistent with this, the mutations in six previously identified yeast mutant PolD2 proteins map within conserved regions III, VI, VII and VIII. Several of the invariant amino acids are also conserved across the archaeal DNA polymerase II DP1 protein family.
DNA聚合酶δ（Pol δ）在真核细胞的DNA复制、修复和重组中起关键作用，它至少由两个必需亚基组成——一个具有DNA聚合酶和3'-5'核酸外切酶活性的大型催化亚基（PolD1），以及一个功能尚不清楚的较小亚基（PolD2）。在此，我们描述了非洲爪蟾编码PolD2亚基同源物的cDNA的克隆和测序。这种蛋白质（命名为XlCdc1）与人类PolD2蛋白质有69%的同一性，与裂殖酵母Cdc1有34%的同一性。对十个真核生物物种的PolD2蛋白质序列进行比对，确定了36个不变氨基酸位置。这36个残基位于十个可能具有关键功能作用的保守区域（命名为I-X）内。与此一致的是，六个先前鉴定的酵母突变型PolD2蛋白质中的突变位于保守区域III、VI、VII和VIII内。几个不变氨基酸在古细菌DNA聚合酶II DP1蛋白质家族中也保守。
