p-Topo IIα Antibody (Thr 1343): sc-16742

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DNA topoisomerase I and II (Topo I and Topo II) are nuclear enzymes that regulate the topological structure of DNA in eukaryotic cells by transiently breaking and rejoining DNA strands. Topo I introduces a transient break in one strand of DNA. Topo II acts by making a transient double-strand break. Topo II is encoded by two different genes, which generate two distinct isoforms, designated Topo IIå and Topo II∫. Topo II∫ and Topo IIå are largely homologous at their N-termini, but differ at their C-termini, suggesting that these regions may mediate different cellular functions and account for their differential tissue expression patterns. Topo IIå is expressed in a cell-cycle-dependent manner, with the highest levels during late G2 phase. Topo IIå is also phosphorylated in a cell-cycle dependent manner, with maximal phosphorylation during G2/M phase. Although Topo IIå is maximally phosphorylated on serine and threonine residues during G2/M phase, the CKII-dependent phosphorylation of Thr-1342 (Thr-1343 corresponds to the sequence including the Methionine start codon) of Topo IIå occurs only in M phase, suggesting a mitosis-specific phosphorylation event.