In the Caenorhabditis elegans zygote, PAR protein patterns, driven by mutual anatagonism, determine the anterior-posterior axis and facilitate the redistribution of proteins for the first cell division. Yet, the factors that determine the selection of the polarity axis remain unclear. We present a reaction-diffusion model in realistic cell geometry, based on biomolecular reactions and accounting for the coupling between membrane and cytosolic dynamics. We find that the kinetics of the phosphorylation-dephosphorylation cycle of PARs and the diffusive protein fluxes from the cytosol towards the membrane are crucial for the robust selection of the anterior-posterior axis for polarisation. The local ratio of membrane surface to cytosolic volume is the main geometric cue that initiates pattern formation, while the choice of the long-axis for polarisation is largely determined by the length of the aPAR-pPAR interface, and mediated by processes that minimise the diffusive fluxes of PAR proteins between cytosol and membrane.

中文翻译：

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几何线索稳定了秀丽隐杆线虫PAR蛋白模式的长轴极化。

在秀丽隐杆线虫合子中，由相互拮抗作用驱动的PAR蛋白模式决定了前后轴，并促进了第一次细胞分裂时蛋白质的重新分布。然而，决定极性轴选择的因素仍然不清楚。我们提出了一种基于生物分子反应并考虑到膜与胞质动力学之间的耦合的现实细胞几何结构中的反应扩散模型。我们发现，PARs磷酸化-去磷酸化循环的动力学以及从细胞质向膜的扩散性蛋白通量对于极化的前后轴的鲁棒选择至关重要。膜表面与胞浆体积的局部比率是引发图案形成的主要几何线索，