Large cytoplasmic ribonucleoprotein particles that have an eight-fold symmetry with a central pore and petal-like structure giving the appearance of an octagonal dome. (The Dictionary of Cell Biology, Lackie and Dow, 2nd ed.)

Complexes of RNA-binding proteins with ribonucleic acids (RNA).

Highly conserved nuclear RNA-protein complexes that function in RNA processing in the nucleus, including pre-mRNA splicing and pre-mRNA 3'-end processing in the nucleoplasm, and pre-rRNA processing in the nucleolus (see RIBONUCLEOPROTEINS, SMALL NUCLEOLAR).

A family of ribonucleoproteins that were originally found as proteins bound to nascent RNA transcripts in the form of ribonucleoprotein particles. Although considered ribonucleoproteins they are primarily classified by their protein component. They are involved in a variety of processes such as packaging of RNA and RNA TRANSPORT within the nucleus. A subset of heterogeneous-nuclear ribonucleoproteins are involved in additional functions such as nucleocytoplasmic transport (ACTIVE TRANSPORT, CELL NUCLEUS) of RNA and mRNA stability in the CYTOPLASM.

Proteins conjugated with nucleic acids.

A nuclear RNA-protein complex that plays a role in RNA processing. In the nucleoplasm, the U1 snRNP along with other small nuclear ribonucleoproteins (U2, U4-U6, and U5) assemble into SPLICEOSOMES that remove introns from pre-mRNA by splicing. The U1 snRNA forms base pairs with conserved sequence motifs at the 5'-splice site and recognizes both the 5'- and 3'-splice sites and may have a fundamental role in aligning the two sites for the splicing reaction.

Short chains of RNA (100-300 nucleotides long) that are abundant in the nucleus and usually complexed with proteins in snRNPs (RIBONUCLEOPROTEINS, SMALL NUCLEAR). Many function in the processing of messenger RNA precursors. Others, the snoRNAs (RNA, SMALL NUCLEOLAR), are involved with the processing of ribosomal RNA precursors.

A group of closely related heterogeneous-nuclear ribonucleoproteins of approximately 41-43 kDa in size found in the cell nucleus. Members of this class have been implicated in a variety of processes including splicing, polyadenylation, and nuclear retention of RNA.

A nuclear RNA-protein complex that plays a role in RNA processing. In the nucleoplasm, the U2 snRNP along with other small nuclear ribonucleoproteins (U1, U4-U6, and U5) assemble into SPLICEOSOMES that remove introns from pre-mRNA by splicing. The U2 snRNA forms base pairs with conserved sequence motifs at the branch point, which associates with a heat- and RNAase-sensitive factor in an early step of splicing.

A class of closely related heterogeneous-nuclear ribonucleoproteins of approximately 34-40 kDa in size. Although they are generally found in the nucleoplasm, they also shuttle between the nucleus and the cytoplasm. Members of this class have been found to have a role in mRNA transport, telomere biogenesis and RNA SPLICING.

Nuclear nonribosomal RNA larger than about 1000 nucleotides, the mass of which is rapidly synthesized and degraded within the cell nucleus. Some heterogeneous nuclear RNA may be a precursor to mRNA. However, the great bulk of total hnRNA hybridizes with nuclear DNA rather than with mRNA.

Proteins that bind to RNA molecules. Included here are RIBONUCLEOPROTEINS and other proteins whose function is to bind specifically to RNA.

The ultimate exclusion of nonsense sequences or intervening sequences (introns) before the final RNA transcript is sent to the cytoplasm.

A polynucleotide consisting essentially of chains with a repeating backbone of phosphate and ribose units to which nitrogenous bases are attached. RNA is unique among biological macromolecules in that it can encode genetic information, serve as an abundant structural component of cells, and also possesses catalytic activity. (Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed)

Relating to the size of solids.

A heterogeneous-nuclear ribonucleoprotein found in the CELL NUCLEUS and the CYTOPLASM. Heterogeneous-nuclear ribonucleoprotein K has been implicated in the regulation of gene expression at nearly all levels: GENETIC TRANSCRIPTION; mRNA processing (RNA PROCESSING, POST-TRANSCRIPTIONAL), mRNA transport, mRNA stability, and translation (TRANSLATION, GENETIC). The hnRNP protein has a strong affinity for polypyrimidine-rich RNA and for single-stranded polypyrimidine-rich DNA. Multiple hnRNP K protein isoforms exist due to alternative splicing and display different nucleic-acid-binding properties.

RNA transcripts of the DNA that are in some unfinished stage of post-transcriptional processing (RNA PROCESSING, POST-TRANSCRIPTIONAL) required for function. RNA precursors may undergo several steps of RNA SPLICING during which the phosphodiester bonds at exon-intron boundaries are cleaved and the introns are excised. Consequently a new bond is formed between the ends of the exons. Resulting mature RNAs can then be used; for example, mature mRNA (RNA, MESSENGER) is used as a template for protein production.

Organelles in which the splicing and excision reactions that remove introns from precursor messenger RNA molecules occur. One component of a spliceosome is five small nuclear RNA molecules (U1, U2, U4, U5, U6) that, working in conjunction with proteins, help to fold pieces of RNA into the right shapes and later splice them into the message.

A nuclear RNA-protein complex that plays a role in RNA processing. In the nucleoplasm, the U4-U6 snRNP along with the U5 snRNP preassemble into a single 25S particle that binds to the U1 and U2 snRNPs and the substrate to form mature SPLICEOSOMES. There is also evidence for the existence of individual U4 or U6 snRNPs in addition to their organization as a U4-U6 snRNP.

The protein components that constitute the common core of small nuclear ribonucleoprotein particles. These proteins are commonly referred as Sm nuclear antigens due to their antigenic nature.

Nucleolar RNA-protein complexes that function in pre-ribosomal RNA processing.

Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.

The first continuously cultured human malignant CELL LINE, derived from the cervical carcinoma of Henrietta Lacks. These cells are used for VIRUS CULTIVATION and antitumor drug screening assays.

The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.

Small RNAs found in the cytoplasm usually complexed with proteins in scRNPs (RIBONUCLEOPROTEINS, SMALL CYTOPLASMIC).

Within a eukaryotic cell, a membrane-limited body which contains chromosomes and one or more nucleoli (CELL NUCLEOLUS). The nuclear membrane consists of a double unit-type membrane which is perforated by a number of pores; the outermost membrane is continuous with the ENDOPLASMIC RETICULUM. A cell may contain more than one nucleus. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)

The spatial arrangement of the atoms of a nucleic acid or polynucleotide that results in its characteristic 3-dimensional shape.

A nuclear RNA-protein complex that plays a role in RNA processing. In the nucleoplasm, the U5 snRNP along with U4-U6 snRNP preassemble into a single 25S particle that binds to the U1 and U2 snRNPs and the substrate to form SPLICEOSOMES.

A heterogeneous-nuclear ribonucleoprotein found associated with the NUCLEAR MATRIX.

Complexes of scRNA (RNA, SMALL CYTOPLASMIC) and protein found in the cytoplasm. An example is SIGNAL RECOGNITION PARTICLE.

RNA sequences that serve as templates for protein synthesis. Bacterial mRNAs are generally primary transcripts in that they do not require post-transcriptional processing. Eukaryotic mRNA is synthesized in the nucleus and must be exported to the cytoplasm for translation. Most eukaryotic mRNAs have a sequence of polyadenylic acid at the 3' end, referred to as the poly(A) tail. The function of this tail is not known for certain, but it may play a role in the export of mature mRNA from the nucleus as well as in helping stabilize some mRNA molecules by retarding their degradation in the cytoplasm.