Fig. 3
From: The role of CPEB family proteins in the nervous system function in the norm and pathology
Functions of the CPEB proteins in neurons. a Scheme of a synapse summarizes the processes described below. 1. CPEB transports translationally silent mRNA as part of a RNP complex along microtubules with the help of the kinesin and dynein motor proteins. 2. CPEBs act as translational repressors in their basal state and are activated by different enzymes after synaptic stimulation. Drosophila Orb2 is phosphorylated by protein kinase LimK; vertebrate CPEBs are phosphorylated by kinase Aurora A, ubiquitinated by Neuralized1, and deSUMOylated by proteases. 3. Activated CPEBs induce polyadenylation of mRNA and activation of protein synthesis. Orb2 and CPEB3 form oligomers, while CPEB1 and CPEB2 function as monomers. Endocytic vesicles with receptors on the scheme of a synapse demonstrate the role of CPEB2 in regulation of the GRASP1 protein, involved in recycling and maintaining the surface level of AMPA receptors. b CPEB4 is necessary for neuronal survival under stress conditions of hypoxia and hypoglycemia and is localized in the nuclei of neurons