摘要 : Proteasomes have been purified from sunflower hypocotyles. They elute with a molecular mass of 600 kDa from gel filtration columns and two-dimensional gel electrophoresis indicates that the complex contains at least 20 different p... 展开 Proteasomes have been purified from sunflower hypocotyles. They elute with a molecular mass of 600 kDa from gel filtration columns and two-dimensional gel electrophoresis indicates that the complex contains at least 20 different protein subunits. Peptide microsequencing revealed the presence of four subunits homologous to subunits Beta2, Beta6, Alpha5 and Alpha6 of plant proteasomes. These proteasomes have chymotrypsin-like activity and the highly purified fraction of this complex i associated with an endonuclease activity hydrolyzing Tobacco mosaic virus RNA and Lettuce mosaic virus RNA wit a cleavage pattern showing fragments of well-define size. this is the first evidence of a RNA endonuclease activity associated with plant proteasomes. 收起