Why do cells need an assembly machine for RNA-protein complexes?
Small nuclear ribonucleoproteins (snRNPs) are crucial for pre-mRNA processing to mRNAs. Each snRNP contains a small nuclear RNA (snRNA) and an extremely stable core of seven Sm proteins. The snRNP biogenesis pathway is complex, involving nuclear export of snRNA, Sm-core assembly in the cytoplasm and re-import of the mature snRNP. Although in vitro Sm cores assemble readily on uridine-rich RNAs, the assembly in cells is carried out by the survival of motor neurons (SMN) complex. The SMN complex stringently scrutinizes RNAs for specific features that define them as snRNAs and identifies the RNA-binding Sm proteins. We discuss how this surveillance capacity of the SMN complex might ensure assembly of Sm cores only on the correct RNAs and prevent illicit, potentially deleterious assembly of Sm cores on random RNAs.
Yong
Jeongsik
J
Howard Hughes Medical Institute, Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6148, USA.
Wan
Lili
L
Dreyfuss
Gideon
G
D000818:Animals; D001483:Base Sequence; D017362:Cyclic AMP Response Element-Binding Protein; D006801:Humans; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D012313:RNA / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016601:RNA-Binding Proteins; D017411:Ribonucleoproteins, Small Nuclear / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D055532:SMN Complex Proteins; D017381:Spliceosomes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity
D017362:Cyclic AMP Response Element-Binding Protein; D009419:Nerve Tissue Proteins; D016601:RNA-Binding Proteins; D017411:Ribonucleoproteins, Small Nuclear; D055532:SMN Complex Proteins; D012313:RNA