Figure 1.

mRNA localization requires multiple factors. The mRNA to be localized is recognized by RNA-binding proteins (RBPs, in red) that interact with linear or structured localization signals, or cis-acting elements, on the mRNA. These RBPs can recruit adaptor proteins (in blue), which mediate anchoring or transport of the localizing messenger ribonucleoprotein complex (mRNP) along the cytoskeleton through the action of molecular motors (in gray). Other proteins (in teal) are required to maintain the mRNP in a translationally repressed state, for example by competing directly with components of the translation machinery (e.g.: Cup) or by recruiting the CCR4:NOT complex to promote shortening of the poly(A) tail on the target mRNA (e.g.: Smg, Nos, Pum). Special RBPs are represented by the Exon Junction Complex (EJC, in orange), the cap-binding protein eIF4E (in green) and the Poly(A)-Binding Protein (PABP, in purple). Asterisks (*) indicate proteins with no known ortholog in vertebrates. Not all of the proteins depicted here will associate at the same time point, or to the same mRNA.