Bonza M C, Fusca T, Homann U, Thiel G, De Michelis M I
Dipartimento di Biologia, Università degli Studi di Milano, Istituto di Biofisica del CNR-Sezione di Milano, Milano, Italy.
Plant Biol (Stuttg). 2009 Nov;11(6):869-77. doi: 10.1111/j.1438-8677.2008.00181.x.
PPI1 (proton pump interactor isoform 1) is a novel protein able to interact with the C-terminal autoinhibitory domain of the Arabidopsis thaliana plasma membrane (PM) H(+)-ATPase. In vitro, PPI1 binds the PM H(+)-ATPase in a site different from the known 14-3-3 binding site and stimulates its activity. In this study, we analysed the intracellular localisation of PPI1. The intracellular distribution was monitored in A. thaliana cultured cells by immunolocalisation using an antiserum against the PPI1 N-terminus and in Vicia faba guard cells and epidermal cells by transient expression of a GFP::PPI1 fusion. The results indicate that the bulk of PPI1 is localised at the endoplasmic reticulum, from which it might be recruited to the PM for interaction with the H(+)-ATPase in response to as yet unidentified signals.
PPI1（质子泵相互作用因子同工型1）是一种新型蛋白质，能够与拟南芥质膜（PM）H(+) -ATP酶的C末端自抑制结构域相互作用。在体外，PPI1在一个不同于已知14-3-3结合位点的位点结合PM H(+) -ATP酶，并刺激其活性。在本研究中，我们分析了PPI1的细胞内定位。通过使用针对PPI1 N末端的抗血清进行免疫定位，在拟南芥培养细胞中监测细胞内分布，并通过GFP::PPI1融合蛋白的瞬时表达，在蚕豆保卫细胞和表皮细胞中监测细胞内分布。结果表明，大部分PPI1定位于内质网，可能会根据尚未确定的信号从内质网被招募到质膜，与H(+) -ATP酶相互作用。
