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 (By similarity). Preferentially binds to N6-methyladenosine (m6A)-containing mRNAs and increases their stability (By similarity). Binds to the 5'-UTR of the insulin-like growth factor 2 (IGF2) mRNAs. Binding is isoform-specific. Binds to beta-actin/ACTB and MYC transcripts (By similarity). Increases MYC mRNA stability by binding to the coding region instability determinant (CRD) and binding is enhanced by m6A-modification of the CRD (By similarity). Can form homooligomers and heterooligomers with IGF2BP1 and IGF2BP3 in an RNA-dependent manner. Interacts with HNRPD. Interacts with IGF2BP1. Interacts with ELAVL1, DHX9, HNRNPU, MATR3 and PABPC1. Localized in cytoplasmic mRNP granules containing untranslated mRNAs. Localizes at the connecting piece and the tail of the spermatozoa. In response to cellular stress, such as oxidative stress, recruited to stress granules (By similarity). Domain KH3 and KH4 are the major RNA-binding modules, although KH1 and KH2 may also contribute. 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. Belongs to the RRM IMP/VICKZ family.