Nuclear matrix isolated from plant cells.

Residual nuclear matrices can be successfully obtained from isolated nuclei of different monocot and dicot plant species using either high ionic or low ionic extraction protocols. The protein composition of isolated nuclear matrices depends on the details of isolation protocols. They are stable and present in all cases, a tripartite organization with a lamina, nucleolar matrix, and internal matrix network, and also maintain some of the basic architectural features of intact nuclei. In situ preparations demonstrate the continuity between the nuclear matrix and the plant cytoskeleton. Two-dimensional separation of isolated plant nuclear matrix proteins reveals a heterogeneous polypeptide composition corresponding rather to a complex multicomponent matrix than to a simple nucleoskeletal structure. Immunological identification of some plant nuclear matrix components such as A and B type lamins, topoisomerase II, and some components of the transcription and splicing machineries, internal intermediate filament proteins, and also specific nucleolar proteins like fibrillarin and nucleolin, which associate to specific matrix domains, establish a model of organization for the plant nuclear matrix similar to that of other eukaryotes. Components of the transcription, processing, and DNA-anchoring complexes are associated with a very stable nucleoskeleton. The plant matrix-attached regions share structural and functional characteristics with those of insects, vertebrates, and yeast, and some of them are active in animal cells. In conclusion, the available data support the view that the plant nuclear matrix is basically similar in animal and plant systems, and has been evolutionarily conserved in eukaryotes.