Promotes phosphorylation of the Wnt coreceptor LRP6, leading to increased activity of the canonical Wnt signaling pathway (By similarity). Facilitates constitutive LRP6 phosphorylation by CDK14/CCNY during G2/M stage of the cell cycle, which may potentiate cells for Wnt signaling (By similarity). May regulate the transport and translation of mRNAs, modulating for instance the expression of proteins involved in synaptic plasticity in neurons (PubMed:20516077). Involved in regulation of growth as erythroblasts shift from a highly proliferative state towards their terminal phase of differentiation (By similarity). May be involved in apoptosis (By similarity). Homotrimer; via C1q domain. Found in a complex with LRP6, CCNY and CDK14 during G2/M stage; CAPRIN2 functions as a scaffold for the complex by binding to CCNY via its N terminus and to CDK14 via its C terminus. Interacts with LRP5. Interacts with LRP6. Specifically expressed in brain (at protein level). Detected at 17.5 dpc in brain (at protein level). The C1q domain is essential for the function in Wnt signaling. Belongs to the caprin family. Extended N-terminus.