small nuclear ribonucleoprotein complex

Definition

Target type: cellularcomponent

A ribonucleoprotein complex that contains at least one RNA of the small nuclear RNA (snRNA) class and as well as its associated proteins. These are typically named after the snRNA(s) they contain, e.g. U1 snRNP, U4/U6 snRNP, or 7SK snRNP. Many, of these complexes become part of the spliceosome involved in splicing of nuclear mRNAs. Others are involved in regulation of transcription elongation or 3'-end processing of replication-dependent histone pre-mRNAs. [GOC:krc, GOC:mah, ISBN:0879695897]

The small nuclear ribonucleoprotein (snRNP) complex is a fundamental component of the spliceosome, the cellular machinery responsible for removing introns from precursor messenger RNA (pre-mRNA) during gene expression. snRNPs are composed of small nuclear RNAs (snRNAs) and associated proteins. These complexes assemble into a dynamic structure that recognizes splice sites, aligns pre-mRNA, and catalyzes the removal of introns. The snRNPs involved in splicing are U1, U2, U4, U5, and U6. Each snRNP contains a unique snRNA molecule and a set of specific proteins. The snRNA molecules fold into complex secondary structures that are crucial for their interactions with the pre-mRNA and with other snRNPs. The proteins associated with snRNAs have diverse functions, including:

* **RNA binding:** Proteins bind to specific sequences within snRNAs, stabilizing their structure and facilitating interactions with other snRNPs.
* **Pre-mRNA binding:** Proteins recognize specific sequences within the pre-mRNA, including splice sites and branch point sequences.
* **Spliceosome assembly:** Proteins mediate the interactions between different snRNPs, bringing them together in a precise order to form the functional spliceosome.
* **Catalytic activity:** Some proteins possess enzymatic activity, such as the catalytic activity of the U2 snRNP that is essential for the splicing reaction.

The snRNP complex undergoes dynamic rearrangements throughout the splicing process, as the snRNPs associate and dissociate from each other and from the pre-mRNA. This dynamic interplay between the snRNPs, the pre-mRNA, and the spliceosome proteins ensures the accurate and efficient removal of introns, a crucial step in gene expression.
'
"

Proteins (1)

Compounds (1)