Suriapranata I, Epple U D, Bernreuther D, Bredschneider M, Sovarasteanu K, Thumm M
Institut fuer Biochemie, Universitaet Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart.
J Cell Sci. 2000 Nov;113 ( Pt 22):4025-33. doi: 10.1242/jcs.113.22.4025.
Autophagy is a degradative transport pathway that delivers cytosolic proteins to the lysosome (vacuole). Cytosolic proteins appear inside the vacuole enclosed in autophagic vesicles. These autophagic vesicles are broken down in the vacuole together with their cytosolic content. The breakdown of vesicular transport intermediates is a unique feature of autophagy. We here identify Aut4p, a component essential for the disintegration of autophagic vesicles, inside the vacuole of S. cerevisiae cells. Aut4p is a putative integral membrane protein with limited homologies to permeases. Chromosomal deletion of AUT4 has no obvious influence on growth, vacuolar acidification and the activities of vacuolar proteinases. Like proteinase B-deficient cells, aut4-deleted cells show a partial reduction in total protein breakdown during nitrogen starvation. A biologically active fusion protein of Aut4p and the green fluorescent protein is visualized at the vacuolar membrane and in punctate structures attached to the vacuole.
自噬是一种将胞质蛋白运输至溶酶体（液泡）进行降解的途径。胞质蛋白出现在被自噬小泡包裹的液泡内部。这些自噬小泡在液泡中与其胞质内容物一同被分解。囊泡运输中间体的分解是自噬的一个独特特征。我们在此鉴定出Aut4p，它是酿酒酵母细胞液泡内自噬小泡分解所必需的一个组分。Aut4p是一种推定的整合膜蛋白，与通透酶有有限的同源性。AUT4的染色体缺失对生长、液泡酸化和液泡蛋白酶的活性没有明显影响。与缺乏蛋白酶B的细胞一样，缺失aut4的细胞在氮饥饿期间总蛋白分解有部分减少。Aut4p与绿色荧光蛋白的生物活性融合蛋白在液泡膜以及附着于液泡的点状结构中可见。
