Abstract
Research over the last two decades has identified a group of meiosis-specific proteins, consisting of budding yeast Spo13, fission yeast Moa1, mouse MEIKIN, and Drosophila Mtrm, with essential functions in meiotic chromosome segregation. These proteins, which we call meiosis I kinase regulators (MOKIRs), mediate two major adaptations to the meiotic cell cycle to allow the generation of haploid gametes from diploid mother cells. Firstly, they promote the segregation of homologous chromosomes in meiosis I (reductional division) by ensuring that sister kinetochores face towards the same pole (mono-orientation). Secondly, they safeguard the timely separation of sister chromatids in meiosis II (equational division) by counteracting the premature removal of pericentromeric cohesin, and thus prevent the formation of aneuploid gametes. Although MOKIRs bear no obvious sequence similarity, they appear to play functionally conserved roles in regulating meiotic kinases. Here, the known functions of MOKIRs are reviewed and their possible mechanisms of action are discussed. Also see the video abstract here https://youtu.be/tLE9KL89bwk.
Highlights
Introduction sis IMeiotic recombination is a complex process that involves the creation of doubl-strand breaks on chromosomes, Eukaryotic cells proliferate and divide by one of two different modes
Mitotic cells first replicate their DNA before segregating sister chromatids to opposite poles
Sister kinetochores must face toward the same pole to co-segregate in meiosis I
Summary
In terms of primary protein sequence, the conservation between MOKIRs is extremely poor. We speculate that a possible explanation for the lack of a clear 3D structure is that the shape of these proteins is largely determined by protein interactions, which could be facilitated by posttranslational modifications, as is frequently observed for intrinsically disordered proteins.[9] all four proteins carry a large number of serine and threonine residues (Figure 2B), which are targets for phosphorylation. Both Moa1MOKIR[10] and Spo13MOKIR[11,12] have been found to be phosphorylated. Despite their strong evolutionary divergence at the sequence level, it is possible that MOKIRs have retained similar conserved molecular functions
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