Insulin-like growth factor 2 mRNA-binding protein 1 - O42254 (IF2B1_CHICK)

 

Protein Feature View of PDB entries mapped to a UniProtKB sequence  

  • Number of PDB entries for O42254: 2
 
Function
RNA-binding factor that recruits target transcripts to cytoplasmic protein-RNA complexes (mRNPs). This transcript 'caging' into mRNPs allows mRNA transport and transient storage. It also modulates the rate and location at which target transcripts encounter the translational apparatus and shields them from endonuclease attacks or microRNA-mediated degradation. Plays a direct role in the transport and translation of transcripts required for axonal regeneration in adult sensory neurons (By similarity). Regulates localized beta-actin/ACTB mRNA translation in polarized cells, a crucial process for cell migration and neurite outgrowth. Co-transcriptionally associates with the ACTB mRNA in the nucleus. This binding involves by a conserved 54-nucleotide element in the ACTB mRNA 3'-UTR, known as the 'zipcode'. The ribonucleoparticle (RNP) thus formed is exported to the cytoplasm, binds to a motor protein and is transported along the cytoskeleton to the cell periphery. During transport, IGF2BP1 prevents beta-actin mRNA from being translated into protein. When the RNP complex reaches its destination near the plasma membrane, IGF2BP1 is phosphorylated by SRC. This releases the mRNA, allowing ribosomal 40S and 60S subunits to assemble and initiate ACTB protein synthesis. The monomeric ACTB protein then assembles into the subcortical actin cytoskeleton, which pushes the leading edge onwards. Binds MYC mRNA. Promotes the directed movement of cells by fine-tuning intracellular signaling networks. Binds to MAPK4 3'-UTR and inhibits its translation. Interacts with PTEN transcript open reading frame (ORF) and prevents mRNA decay. This combined action on MAPK4 (down-regulation) and PTEN (up-regulation) antagonizes HSPB1 phosphorylation, consequently it prevents G-actin sequestration by phosphorylated HSPB1, allowing F-actin polymerization. Hence enhances the velocity of cell migration and stimulates directed cell migration by PTEN-modulated polarization. UniProt
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Subunit Structure
Can form homooligomers and heterooligomers with IGF2BP1 and IGF2BP3 in an RNA-dependent manner. Associates with the cytoskeleton, predominantly with actin filament bundles and occasionally with microtubules. In a heterologous system, interacts with ELAVL1, DHX9 and HNRNPU. UniProt
Domain
Domain KH3 and KH4 are the major RNA-binding modules, although KH1 and KH2 may also contribute to transcript binding. The contribution to RNA-binding of individual KH domains may be target-specific. KH1 and KH2, and possibly KH3 and KH4, promote the formation of higher ordered protein-RNA complexes, which may be essential for IGF2BP1 cytoplasmic retention. KH domains are required for RNA-dependent homo- and heterooligomerization and for localization to stress granules. KH3 and KH4 mediate association with the cytoskeleton. Two nuclear export signals (NES) have been identified in KH2 and KH4 domains, respectively. Only KH2 NES is XPO1-dependent. Both NES may be redundant, since individual in vitro mutations do not affect subcellular location of the full length protein. UniProt
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The PDB to UniProt mapping is based on the data provided by the EBI SIFTS project. See also Velankar et al., Nucleic Acids Research 33, D262-265 (2005).
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