High impact information on thr

• Our observations suggest that Pimples and Three rows act during mitosis to release the cohesion between sister centromeres [1].
• This lethality can be suppressed by a reduction of catalytically active SSE levels, indicating that THR cleavage inactivates SSE complexes [2].
• Proteolytic cleavage of the THR subunit during anaphase limits Drosophila separase function [2].
• Mitotic defects in thr mutant embryos begin during mitosis 15, and all subsequent divisions are disrupted [3].
• These observations, together with the observation that the zygotic phenotype of thr mutant embryos is influenced by the maternal genotype, suggest that the embryonic phenotype results from exhaustion of the maternal thr contribution and does not reflect a developmentally restricted requirement for thr function [3].

Biological context of thr

• THR cleavage is particularly important during the process of cellularization, which follows completion of the last syncytial mitosis of early embryogenesis, suggesting that Drosophila separase has other targets in addition to cohesin subunits [2].
• Zygotic expression of the three rows (thr) gene of Drosophila melanogaster is required for normal cell proliferation during embryogenesis [3].
• We have cloned the three rows (thr) gene, by a combination of chromosome microdissection and P element tagging [4].
• Chromosomes in the cells of thr embryos do not undertake anaphase separation, but remain at the metaphase plate [4].
• Drosophila PIM and THR are required for sister chromatid separation in mitosis and associate in vivo [5].

Anatomical context of thr

• However, a small percentage of cells in syncytial blastoderm stage thr embryos sink into the interior of the embryo as if they have failed to divide properly [4].
• As cyclin B degradation occurs at the metaphase-anaphase transition, subsequent to the microtubule integrity checkpoint, the delay induced by mutations at the thr locus defines a later point in mitotic progression [4].

Associations of thr with chemical compounds

• Whereas these securins are known to form a complex with separins, we show that PIM associates in vivo with THR, which does not contain the conserved separin domain [6].

Enzymatic interactions of thr

• These results indicate that THR is cleaved by SSE [2].

Other interactions of thr

• The family of ser/thr protein phosphatases 2A (PP2A) is a major regulator of cell proliferation and cell death and is critically involved in the maintenance of homeostasis [7].

References