Promotes phosphorylation of the Wnt coreceptor LRP6, leading to increased activity of the canonical Wnt signaling pathway. Facilitates constitutive LRP6 phosphorylation by CDK14/CCNY during G2/M stage of the cell cycle, which may potentiate cells for Wnt signaling. May regulate the transport and translation of mRNAs, modulating for instance the expression of proteins involved in synaptic plasticity in neurons. Involved in regulation of growth as erythroblasts shift from a highly proliferative state towards their terminal phase of differentiation. May be involved in apoptosis. Homotrimer; via C1q domain. The C1q domain is essential for the function in Wnt signaling. Morpholino knockdown results in a dorsalized phenotype, with enlargement of the telencephalon and reduction of the tail at 24 hours post-fertilization. Expression of the dorsal marker goosecoid is expanded, whereas expression of the ventral markers eve1 and tbx6 is reduced. In addition, expression of the telencephalon marker opl and the midbrain/hindbrain boundary marker pax2.1 is expanded posteriorly. Belongs to the caprin family.