Fleckenstein D, Rohde M, Klionsky D J, Rüdiger M
Cell Biology - Zoological Institute, Spielmannstrasse 7, Germany. m.
J Cell Sci. 1998 Oct;111 ( Pt 20):3109-18. doi: 10.1242/jcs.111.20.3109.
Proteins of the armadillo family are involved in diverse cellular processes in higher eukaryotes. Some of them, like armadillo, beta-catenin and plakoglobins have dual functions in intercellular junctions and signalling cascades. Others, belonging to the importin-alpha-subfamily are involved in NLS recognition and nuclear transport, while some members of the armadillo family have as yet unknown functions. Here, we introduce the Saccharomyces cerevisiae protein Yel013p as a novel armadillo (arm) repeat protein. The ORF Yel013w was identified in the genome project on chromosome V (EMBL: U18530) and codes for an acidic protein of 578 residues with 8 central arm-repeats, which are closely related to the central repeat-domain of Xenopus laevis plakoglobin. We show that Yel013p (Vac8p) is constitutively expressed in diploid and haploid yeasts and that it is not essential for viability and growth. However, the vacuoles of mutant cells are multilobular or even fragmented into small vesicles and the processing of aminopeptidase I, representing the cytoplasm-to-vacuole transport pathway, is strongly impaired. Consistent with these observations, subcellular fractionation experiments, immunolocalization and expression of green fluorescent protein (GFP) fusion proteins revealed that Yel013p (Vac8p) is associated with the vacuolar membrane. Our data provide evidence for the involvement of an arm-family member in vacuolar morphology and protein targeting to the vacuole.
犰狳家族的蛋白质参与高等真核生物的多种细胞过程。其中一些，如犰狳蛋白、β-连环蛋白和桥粒斑蛋白，在细胞间连接和信号级联反应中具有双重功能。其他属于输入蛋白α亚家族的蛋白质参与核定位信号识别和核运输，而犰狳家族的一些成员功能尚不清楚。在此，我们介绍酿酒酵母蛋白Yel013p，它是一种新型的犰狳（arm）重复蛋白。ORF Yel013w在第五条染色体的基因组计划（EMBL：U18530）中被鉴定出来，编码一个由578个残基组成的酸性蛋白，含有8个中央arm重复序列，与非洲爪蟾桥粒斑蛋白的中央重复结构域密切相关。我们发现Yel013p（Vac8p）在二倍体和单倍体酵母中组成性表达，对细胞活力和生长并非必需。然而，突变细胞的液泡呈多叶状，甚至破碎成小泡，代表细胞质到液泡运输途径的氨肽酶I的加工过程受到严重损害。与这些观察结果一致，亚细胞分级分离实验、免疫定位和绿色荧光蛋白（GFP）融合蛋白的表达表明Yel013p（Vac8p）与液泡膜相关。我们的数据为犰狳家族成员参与液泡形态和蛋白质靶向液泡提供了证据。
