Association of small nuclear RNA-protein complex with the nuclear matrix from bovine lymphocytes.

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A nuclear matrix obtained from bovine lymphocytes contained a large number of small nuclear RNAs (snRNAs) : 30 % Ul +5.8SRNA, 65 U2RNA, 82 % U3RNA, 44 % U4RNA, 45 % U5RNA and 55 % U6RNA from isolated nuclei. These RNAs were tightly associated as a small nuclear RNA-protein complex (snRNPs) on the nuclear matrix, but they could be dissociated by treatment with high salt buffer or by sonication. When dissociated by this treatments, subsets of RNPs containing differentsnRNAs were found in the same fractions after centrifugation of a sucrose density gradient. In contrast, snRNPs could be dissociated effectively by treatment with a low salt buffer containing 1 mM ATP, 1 mM DTT, 0.4 mM CaC12, 0.2 mM EDTA and 10 % (v/v) formamide. A large portion of the stractural proteins of this nuclear matrix were depolymerized and released from the matrix by this treatment. The dissociated snRNPs had different sedimentation velocities in the sucrose density gradient among snRNPs. When, instead of CaC12 the same concentration of MgCl2 was added, the amount of released snRNPs decreased greatly. These results suggest that snRNPs bind to proteinaceous filaments of the nuclear matrix in diverse ways in spite of the similarities of the snRNP "core particles" themselves.
日本細胞生物学会の論文