Subcellular localization of ubiquitin and ubiquitinated proteins in Arabidopsis thaliana.

摘要: Ubiquitin is a highly conserved, 76-amino acid, eukaryotic protein. Its widely accepted role as proteolytic cofactor depends on its unique ability to covalently ligate other cellular proteins. While there good evidence for the existence of such ubiquitinated proteins in cytosolic and nuclear compartments, relatively little known about presence free ubiquitin subcellular compartments. This especially true higher plants, which have not previously been subject extensive biochemical localizations We extracted cell wall purified nuclei, vacuoles, chloroplasts, microsomes from chlorophyllous tissues Arabidopsis. Immunoblot analyses were used compare profiles fractions those unfractionated extracts. Purified nuclei contained, addition complex mixture high molecular mass proteins, strongly immunoreactive 28-kDa In apoplastic extract, we did detect any enriched above background level due contamination. Vacuoles appeared contribute significantly present whole protoplast extract. At least three vacuolar Chloroplast stromal react specifically with anti-ubiquitin antibodies. When microsomal compared found distinct pattern was evident. Microsomal visible 10,000 x g supernatant prepare 100,000 pellet, indicating that they probably low abundance