mRNA transport in dendrites: RNA granules, motors, and tracks.

The targeting of mRNAs to neuronal dendrites is an important protein sorting mechanism. Recent studies have revealed that mRNAs are transported by molecular motors. The kinesin superfamily protein KIF5 transports mRNAs such as calcium/calmodulin-dependent kinase IIalpha (CaMKIIalpha) and Arc mRNAs along microtubules in large granules containing proteins involved in RNA transport, protein synthesis, RNA helicases, heterogeneous nuclear ribonucleoproteins (hnRNPs), and RNA-associated proteins. This transport is fundamental to local protein synthesis and to the regulation of neuronal function.