Subcellular localization of Axl1, the cell type-specific regulator of polarity
Subcellular localization of Axl1, the cell type-specific regulator of polarity
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DOI：
10.1016/s0960-9822(02)01042-4
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发表时间：
2002-08-06
期刊：
影响因子：
9.2
通讯作者：
Chant, J
中科院分区：
文献类型：
--
作者：
Lord, M;Inose, F;Chant, J
酵母的芽位选择为研究细胞极性和不对称分裂提供了一个有吸引力的系统。单倍体以轴向方式分裂，而二倍体以双极方式分裂。AXL1在单倍体中表达，而在二倍体中不表达，AXL1在二倍体中的异位表达将其双极出芽模式转化为轴向模式。Axl1是如何作为双极和轴向模式之间的开关的还不清楚。在这里，我们报道了Axl1定位于单倍体的母芽颈部和分裂位点残余。二倍体不存在轴l1。Axl1与Bud3、Bud4和Bud10是轴向地标结构的组成部分。这种定位表明，Axl1将轴向标志与下游极性建立因素耦合在一起。与这种作用一致的是，Axl1与Bud4和Buds存在生物化学关联。遗传证据表明，Axl1与Bud3和Bud4共同作用，促进Bud10膜蛋白的活性。考虑到Axl1在交配过程中的形态发生和细胞融合中的作用，我们也研究了它在这一过程中的定位。Axl1独立于轴向标记重新分布到每个交配投影尖端的紧密细胞表面点。这些点随着前受精卵的形成而迅速消失。
Bud-site selection in yeast offers an attractive system for studying cell polarity and asymmetric division. Haploids divide in an axial pattern, whereas diploids divide in a bipolar pattern. AXL1 is expressed in haploids but not diploids, and ectopic expression of AXL1 in diploids converts their bipolar budding pattern to an axial pattern. How Axl1 acts as a switch between the bipolar and axial patterns is not understood. Here we report that Axl1 localizes to the mother-bud neck and division site remnants of haploids. Axl1 is absent from diploids. Axl1 colocalizes with Bud3, Bud4, and Bud10, components of the axial landmark structure. This localization suggests that Axl1 couples the axial landmark with downstream polarity establishment factors. Consistent with such a role, Axl1 associated biochemically with Bud4 and Buds. Genetic evidence suggests that Axl1 works with Bud3 and Bud4 to promote the activity of the Bud10 membrane protein. Given Axl1's suggested role in morphogenesis and cell fusion during mating, we also examined its localization during this process. Axl1 redistributes independently of the axial landmark to a tight cell surface dot at the tip of each mating projection. These dots are rapidly lost as prezygotes form.