Molecular composition of IMP1 ribonucleoprotein granules.

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Jonson L, Vikesaa J, Krogh A, Nielsen LK, Hansen Tv, Borup R, Johnsen AH, Christiansen J, Nielsen FC

Molecular composition of IMP1 ribonucleoprotein granules.

Mol Cell Proteomics. 2007 May;6(5):798-811. Epub 2007 Feb 7.

PubMed ID
17289661 [ View in PubMed
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Abstract

Localized mRNAs are transported to sites of local protein synthesis in large ribonucleoprotein (RNP) granules, but their molecular composition is incompletely understood. Insulin-like growth factor II mRNA-binding protein (IMP) zip code-binding proteins participate in mRNA localization, and in motile cells IMP-containing granules are dispersed around the nucleus and in cellular protrusions. We isolated the IMP1-containing RNP granules and found that they represent a unique RNP entity distinct from neuronal hStaufen and/or fragile X mental retardation protein granules, processing bodies, and stress granules. Granules were 100-300 nm in diameter and consisted of IMPs, 40 S ribosomal subunits, shuttling heterologous nuclear RNPs, poly(A)-binding proteins, and mRNAs. Moreover granules contained CBP80 and factors belonging to the exon junction complex and lacked eIF4E, eIF4G, and 60 S ribosomal subunits, indicating that embodied mRNAs are not translated. Granules embodied mRNAs corresponding to about 3% of the human embryonic kidney 293 mRNA transcriptome. Messenger RNAs encoding proteins participating in the secretory pathway and endoplasmic reticulum-associated quality control, as well as ubiquitin-dependent metabolism, were enriched in the granules, reinforcing the concept of RNP granules as post-transcriptional operons.

DrugBank Data that Cites this Article

Polypeptides
NameUniProt ID
Heat shock cognate 71 kDa proteinP11142Details
Actin, cytoplasmic 1P60709Details
Heterogeneous nuclear ribonucleoproteins A2/B1P22626Details
Heterogeneous nuclear ribonucleoprotein HP31943Details
Heterogeneous nuclear ribonucleoprotein LP14866Details
Heterogeneous nuclear ribonucleoprotein D0Q14103Details
40S ribosomal protein S8P62241Details
40S ribosomal protein S9P46781Details