Molecular composition of IMP1 ribonucleoprotein granules.
Research output: Contribution to journal › Journal article › Research › peer-review
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.
Original language | English |
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Journal | Molecular and Cellular Proteomics |
Volume | 6 |
Issue number | 5 |
Pages (from-to) | 798-811 |
Number of pages | 13 |
ISSN | 1535-9476 |
DOIs | |
Publication status | Published - 2007 |
Bibliographical note
Keywords: Cell Line; Cytoskeletal Proteins; Fragile X Mental Retardation Protein; Humans; Metabolic Networks and Pathways; Microscopy, Atomic Force; Proteomics; RNA, Messenger; RNA-Binding Proteins; Ribonucleoproteins
ID: 6474186