7ww3
Crystal structure of MmIMP1-KH34 tandem domain
Structural highlights
FunctionIF2B1_MOUSE RNA-binding factor that recruits target transcripts to cytoplasmic protein-RNA complexes (mRNPs). This transcript 'caging' into mRNPs allows mRNA transport and transient storage (PubMed:15355996, PubMed:17264115, PubMed:21964071, PubMed:22465430, PubMed:23388827). 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. Preferentially binds to N6-methyladenosine (m6A)-containing mRNAs and increases their stability (By similarity). Regulates localized beta-actin/ACTB mRNA translation, a crucial process for cell polarity, cell migration and neurite outgrowth. Co-transcriptionally associates with the ACTB mRNA in the nucleus. This binding involves a conserved 54-nucleotide element in the ACTB mRNA 3'-UTR, known as the 'zipcode'. The 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, prevents ACTB mRNA from being translated into protein. When the RNP complex reaches its destination near the plasma membrane, IGF2BP1 is phosphorylated. This releases the mRNA, allowing ribosomal 40S and 60S subunits to assemble and initiate ACTB protein synthesis. Monomeric ACTB then assembles into the subcortical actin cytoskeleton (By similarity). During neuronal development, key regulator of neurite outgrowth, growth cone guidance and neuronal cell migration, presumably through the spatiotemporal fine tuning of protein synthesis, such as that of ACTB (By similarity). May regulate mRNA transport to activated synapses (By similarity). Binds to the 3'-UTR of CD44 mRNA and stabilizes it, hence promotes cell adhesion and invadopodia formation in cancer cells (By similarity). Binds to the oncofetal H19 transcript and regulates its localization (By similarity). Binds to and stabilizes BTRC/FBW1A mRNA (By similarity). Binds to the adenine-rich autoregulatory sequence (ARS) located in PABPC1 mRNA and represses its translation. PABPC1 mRNA-binding is stimulated by PABPC1 protein. Prevents BTRC/FBW1A mRNA degradation by disrupting microRNA-dependent interaction with AGO2 (By similarity). During cellular stress, such as oxidative stress or heat shock, stabilizes target mRNAs that are recruited to stress granules, including CD44, IGF2, MAPK4, MYC, PTEN, RAPGEF2 and RPS6KA5 transcripts (By similarity). Interacts with GAP43 transcript and transports it to axons. Binds to the 3'-UTR of IGF2 mRNA by a mechanism of cooperative and sequential dimerization and regulates IGF2 mRNA subcellular localization and translation (PubMed:23388827). Binds to MYC mRNA, in the coding region instability determinant (CRD) of the open reading frame (ORF), hence prevents MYC cleavage by endonucleases and possibly microRNA targeting to MYC-CRD. Binding to MYC mRNA is enhanced by m6A-modification of the CRD (By similarity). Binds to and stabilizes ABCB1/MDR-1 mRNA. Binds to the neuron-specific TAU mRNA and regulates its localization. Plays a direct role in the transport and translation of transcripts required for axonal regeneration in adult sensory neurons. During interstinal wound repair, interacts with and stabilizes PTGS2 transcript. PTGS2 mRNA stabilization may be crucial for colonic mucosal wound healing.[UniProtKB:Q9NZI8][1] [2] [3] [4] [5] Publication Abstract from PubMedIGF2BP family proteins (IGF2BPs) contain six tandem RNA-binding domains (RBDs), resulting in highly complex RNA binding properties. Dissecting how IGF2BPs recognize their RNA targets is essential for understanding their regulatory roles in gene expression. Here, we have determined the crystal structures of mouse IGF2BP3 constructs complexed with different RNA substrates. Our structures reveal that the IGF2BP3-RRM12 domains can recognize CA-rich elements up to 5-nt in length, mainly through RRM1. We also captured the antiparallel RNA-binding mode of the IGF2BP3-KH12 domains, with five nucleotides bound by KH1 and two nucleotides bound by KH2. Furthermore, our structural and biochemical studies suggest that the IGF2BP3-KH12 domains could recognize the "zipcode" RNA element within the beta-actin mRNA. Finally, we analyzed the similarities and differences of the RNA-binding properties between the KH12 and KH34. Our studies provide structural insights into RNA target recognition by mouse IGF2BP3. Structural basis for the RNA binding properties of mouse IGF2BP3.,Li X, Guo W, Wen Y, Meng C, Zhang Q, Chen H, Zhao X, Wu B Structure. 2025 Feb 12:S0969-2126(25)00022-X. doi: 10.1016/j.str.2025.01.022. PMID:39986276[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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