U1, U2, and U6 small nuclear ribonucleoproteins (snRNPs) are associated with large nuclear RNP particles containing transcripts of an amplified gene in vivo.

AUTOR(ES)

Sperling, R

RESUMO

Nuclear ribonucleoprotein (RNP) complexes that contain intact transcripts of the amplified gene for CAD, the multifunctional protein that initiates UMP synthesis in Syrian hamster cells, have been released from nuclei of Syrian hamster cells as large particulate structures that sediment at the 200S region in a sucrose gradient. By the technique of RNA hybridization, we have shown that U1, U2, and U6 small nuclear RNAs (snRNAs) cosediment with the large RNP particles in the sucrose gradients. Autoimmune sera from systemic lupus erythematosus and mixed connective tissue disease patients, characterized as anti-(U1)RNP, have further been shown to immunoprecipitate CAD RNA along with U1 and U2 snRNAs from the fractionated nuclear 200S RNP particles. We conclude that U1, U2, and U6 snRNPs are integral constituents of the 200S RNP particles. The requirement of snRNPs for RNA processing that evidently occurs on RNP particles has been recently demonstrated. Our results thus suggest that the 200S RNPs are structurally and functionally close to the native particles on which RNA processing occurs.

Documentos Relacionados

• The low-abundance U11 and U12 small nuclear ribonucleoproteins (snRNPs) interact to form a two-snRNP complex.
• A block in mammalian splicing occurring after formation of large complexes containing U1, U2, U4, U5, and U6 small nuclear ribonucleoproteins.
• Purification of snRNPs U1, U2, U4, U5 and U6 with 2,2,7-trimethylguanosine-specific antibody and definition of their constituent proteins reacting with anti-Sm and anti-(U1)RNP antisera.
• Sm and Sm-like proteins belong to a large family: identification of proteins of the U6 as well as the U1, U2, U4 and U5 snRNPs.
• Pre-mRNA splicing by complementation with purified human U1, U2, U4/U6 and U5 snRNPs.