Atg2 is one of the essential factors for autophagy. Recent advance of structural and biochemical study on yeast Atg2 proposed that Atg2 tethers the edge of the isolation membrane (IM) to the endoplasmic reticulum and mediates direct lipid transfer (LT) from ER to IM for IM expansion. In mammals, two Atg2 orthologs, ATG2A and ATG2B, participate in autophagic process. Here we showed that human ATG2B possesses the membrane tethering (MT) and LT activity that was promoted by negatively charged membranes and an Atg18 ortholog WIPI4. By contrast, negatively charged membranes reduced the yeast Atg2 activities in the absence of Atg18. These results suggest that the MT/LT activity of Atg2 is evolutionally conserved although their regulation differs among species.

中文翻译：

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人ATG2B具有脂质转移活性，该活性被带负电荷的脂质和WIPI4加速。

Atg2是自噬的重要因素之一。酵母Atg2的结构和生化研究的最新进展表明，Atg2将隔离膜（IM）的边缘束缚到内质网，并介导从ER到IM的直接脂质转移（LT），以实现IM扩展。在哺乳动物中，两个Atg2直系同源物ATG2A和ATG2B参与自噬过程。在这里，我们显示人ATG2B具有带负电荷的膜和Atg18直系同源物WIPI4促进的膜束缚（MT）和LT活性。相反，在没有Atg18的情况下，带负电荷的膜会降低酵母的Atg2活性。这些结果表明，Atg2的MT / LT活性在进化上是保守的，尽管它们的调控在物种之间有所不同。