The action of snRNPs is essential to the removal of introns from pre-mRNA, a critical aspect of post-transcriptional modification of RNA, occurring only in the nucleus of eukaryotic cells.
[5] Additionally, U7 snRNP is made of U7 small nuclear RNA and associated proteins and is involved in the processing of the 3′ stem-loop of histone pre-mRNA.
[1] Small nuclear ribonucleoproteins (snRNPs) assemble in a tightly orchestrated and regulated process that involves both the cell nucleus and cytoplasm.
[7] These three Sm proteins have repeated arginine-glycine motifs in the C-terminal ends of SmD1, SmD3 and SmB, and the arginine side chains are symmetrically dimethylated to ω-NG, NG'-dimethyl-arginine.
It has been suggested that pICln, which occurs in all three precursor complexes but is absent in the mature snRNPs, acts as a specialized chaperone, preventing premature assembly of Sm proteins.
This Sm site is a conserved sequence of nucleotides in these snRNAs, typically AUUUGUGG (where A, U and G represent the nucleosides adenosine, uridine and guanosine, respectively).
Defective function of the survival of motor neuron (SMN) protein in snRNP biogenesis, caused by a genetic defect in the SMN1 gene which codes for SMN, may account for the motor neuron pathology observed in the genetic disorder spinal muscular atrophy.
[10] Several human and yeast snRNP structures were determined by the cryo-electron microscopy and successive single particle analysis.
[17] Autoantibodies may be produced against the body's own snRNPs, most notably the anti-Sm antibodies targeted against the Sm protein type of snRNP specifically in systemic lupus erythematosus (SLE).