Lateral diffusion barriers compartmentalize membranes to generate polarity or asymmetrically partition membrane-associated macromolecules. Budding yeasts assemble such barriers in the endoplasmic reticulum (ER) and the outer nuclear envelope at the bud neck to retain aging factors in the mother cell and generate naïve and rejuvenated daughter cells. However, little is known about whether other organelles are similarly compartmentalized. Here, we show that the membranes of mitochondria are laterally compartmentalized at the bud neck and near the cell poles. The barriers in the inner mitochondrial membrane are constitutive, whereas those in the outer membrane form in response to stresses. The strength of mitochondrial diffusion barriers is regulated positively by spatial cues from the septin axis and negatively by retrograde (RTG) signaling. These data indicate that mitochondria are compartmentalized in a fission-independent manner. We propose that these diffusion barriers promote mitochondrial polarity and contribute to mitochondrial quality control.

中文翻译：

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芽殖酵母细胞分裂过程中线粒体的裂变独立区室化


横向扩散屏障将膜分隔开来产生极性或不对称地分隔膜相关大分子。出芽酵母在内质网（ER）和芽颈外核被膜中组装此类屏障，以保留母细胞中的衰老因子，并产生幼稚且恢复活力的子细胞。然而，人们对其他细胞器是否也有类似的划分知之甚少。在这里，我们发现线粒体膜在芽颈和细胞极附近横向划分。线粒体内膜中的屏障是组成性的，而外膜中的屏障是响应应激而形成的。线粒体扩散屏障的强度受到来自隔膜轴的空间线索的正向调节，并受到逆行（RTG）信号的负向调节。这些数据表明线粒体以不依赖裂变的方式划分。我们认为这些扩散障碍促进线粒体极性并有助于线粒体质量控制。