Recycling of the yeast a-factor receptor.
Recycling of the yeast a-factor receptor.
复制标题
酵母A因子受体的回收。
DOI：
10.1083/jcb.151.3.731
复制
发表时间：
2000-10-30
影响因子：
7.8
通讯作者：
Davis, N G
中科院分区：
文献类型：
--
作者：
Chen, L;Davis, N G
酵母α-因子受体(Ste3p)有两种不同的内吞机制：一种是构成的非配体途径，另一种是配体依赖的摄取途径。尽管构成途径会导致液泡中受体的降解，但目前的工作发现，通过配体依赖途径内化的受体可以回收利用。随着α-因子配体持续存在于培养液中，受体的运输达到了平衡，在这种平衡中，持续摄取到内体隔室的平衡是通过其循环返回质膜来平衡的。从介质中撤出配体会导致内化的受体净返回质膜。尽管缺乏结构性内吞信号的受体被证明是循环的，但有证据表明循环也参与了野生型Ste3p的运输：A因子治疗既减缓了野生型受体的周转，又导致了受体重新分配到细胞内的内体间隔。显然，a因子起到了开关的作用，将受体从空泡导向的内吞和降解转移到循环。提出了两种Ste3p内吞模式如何协同产生交配细胞极化受体分布特征的模型。
The yeast a-factor receptor (Ste3p) is subject to two mechanistically distinct modes of endocytosis: a constitutive, ligand-independent pathway and a ligand-dependent uptake pathway. Whereas the constitutive pathway leads to degradation of the receptor in the vacuole, the present work finds that receptor internalized via the ligand-dependent pathway recycles. With the a-factor ligand continuously present in the culture medium, trafficking of the receptor achieves an equilibrium in which continuing uptake to endosomal compartments is balanced by its recycling return to the plasma membrane. Withdrawal of ligand from the medium leads to a net return of the internalized receptor back to the plasma membrane. Although recycling is demonstrated for receptors that lack the signal for constitutive endocytosis, evidence is provided indicating a participation of recycling in wild-type Ste3p trafficking as well: a-factor treatment both slows wild-type receptor turnover and results in receptor redistribution to intracellular endosomal compartments. Apparently, a-factor acts as a switch, diverting receptor from vacuole-directed endocytosis and degradation, to recycling. A model is presented for how the two Ste3p endocytic modes may collaborate to generate the polarized receptor distribution characteristic of mating cells.