Scott S V, Hefner-Gravink A, Morano K A, Noda T, Ohsumi Y, Klionsky D J
Section of Microbiology, University of California, Davis, CA 95616, USA.
Proc Natl Acad Sci U S A. 1996 Oct 29;93(22):12304-8. doi: 10.1073/pnas.93.22.12304.
The vacuolar protein aminopeptidase I (API) uses a novel cytoplasm-to-vacuole targeting (Cvt) pathway. Complementation analysis of yeast mutants defective for cytoplasm-to-vacuole protein targeting (cvt) and autophagy (apg) revealed seven overlapping complementation groups between these two sets of mutants. In addition, all 14 apg complementation groups are defective in the delivery of API to the vacuole. Similarly, the majority of nonoverlapping cvt complementation groups appear to be at least partially defective in autophagy. Kinetic analyses of protein delivery rates indicate that autophagic protein uptake is induced by nitrogen starvation, whereas Cvt is a constitutive biosynthetic pathway. However, the machinery governing Cvt is affected by nitrogen starvation as targeting defects resulting from API overexpression can be rescued by induction of autophagy.
液泡蛋白氨基肽酶I（API）采用一种新型的从细胞质到液泡的靶向（Cvt）途径。对细胞质到液泡蛋白靶向（cvt）和自噬（apg）缺陷的酵母突变体进行的互补分析揭示了这两组突变体之间的七个重叠互补组。此外，所有14个apg互补组在将API递送至液泡方面均存在缺陷。同样，大多数非重叠的cvt互补组似乎在自噬方面至少部分存在缺陷。蛋白质递送速率的动力学分析表明，自噬性蛋白质摄取由氮饥饿诱导，而Cvt是一种组成型生物合成途径。然而，控制Cvt的机制受氮饥饿影响，因为API过表达导致的靶向缺陷可通过诱导自噬来挽救。
