Identification and characterization of the small nuclear ribonucleoprotein particle D' core protein.

Abstract

The addition of urea to sodium dodecyl sulfate (SDS)-polyacrylamide gels has allowed the identification and characterization of the small nuclear ribonucleoprotein particle (snRNP) D Small nuclear ribonucleoprotein particles (snRNPs) contain a unique small nuclear RNA (snRNA) with several snRNP-specific proteins in addition to a common core of proteins shared by almost all the snRNPs. The major snRNPs in the nucleoplasm share a group of core proteins that includes the previously identified B, D, E, F, and G proteins (for reviews, see references 3 and 20a). There are tissue-and species-specific differences in the B protein, including an alternatively spliced B' protein present in most primate but not murine tissues (1Sa, 18). The newly synthesized snRNP core proteins are stored in large snRNA-free pools in the cytoplasm and are available for assembly with newly transcribed snRNAs that appear transiently in the cytoplasm. The snRNP core proteins move into the nucleus after being assembled into snRNPs. The snRNP B protein is the first core protein to accumulate in the nucleus, suggest-

Thirteen Anti-Sm Monoclonal Antibodies Immunoprecipitate the Three Cytoplasmic snRNP Core Protein Precursors in Six Distinct Subsets

“…L929 mouse fibroblasts and HeLa human epithelial cells were grown in suspension culture and metabolically labeled with 35 S-methionine as previously described [25]. Aqueous cytoplasmic fractions were prepared by rinsing cells in phosphate buffered saline (PBS) and resuspending them in CSK buffer (100 mM NaCl, 3 mM MgCl 2 , 10 mM Pipes pH 6.8) containing 0.5% Triton X-100 at 4°C followed by vigorous vortexing.…”

The Methylosome, a 20S Complex Containing JBP1 and pICln, Produces Dimethylarginine-Modified Sm Proteins

“…Based on pulse-chase experiments, it was proposed that the Sm proteins accumulate in 4S-6S complexes prior to assembly into snRNP core particles of approximately 11S (18). Subsequent work also identified SmB and SmD3 in an approximately 20S complex (1,22,50). Anti-Sm protein antibody immunoprecipitation experiments and Sm protein purification identified pre-snRNP Sm protein complexes of B/D3, D1/D2, and E/F/G (48,50).…”

In vitro interaction of U2 snRNA with cytoplasmic 6S protein complexes

“…Lanes 0~ and 0 + contain U2 snRNA incubated in buffer alone without UV radiation (-) and with UV radiation (+). Lane M contains snRNP marker proteins immunopreciptiated from 35 Slabeled nuclear extracts made as previously described [12]. The snRNP proteins in the marker lane are identified at the left.…”

“…After transcription by RNA polymerase II, snRNAs travel to the cytoplasm where they assemble with the common core proteins [10,11]. In the cytoplasm, snRNP proteins are stored in three RNA-free complexes: 2 S-5S (B/B'), 6S (Dl, D2, E, F, G) and 20S (D3, B/B', 69 kDa) [9,12]. Kinetic experiments suggest that the first step in assembly is the binding of the snRNA to the 6S complex in the cytoplasm 'Corresponding author.…”

“…Kinetic experiments suggest that the first step in assembly is the binding of the snRNA to the 6S complex in the cytoplasm 'Corresponding author. [9][10][11][12][13]. The present study analyzes the specific interaction of U2 snRNA, as a representative of the Sm snRNAs, with proteins in the cytoplasmic 6S fraction.…”