May function as a linker between cadherin adhesion receptors and the cytoskeleton to regulate cell-cell adhesion and differentiation in the nervous system (PubMed:12123610, PubMed:15034585). Required for proper regulation of cortical neuronal migration and neurite growth. It acts as negative regulator of Arp2/3 complex activity and Arp2/3-mediated actin polymerization. It thereby suppresses excessive actin branching which would impair neurite growth and stability (By similarity). Regulates morphological plasticity of synapses and cerebellar and hippocampal lamination during development. Functions in the control of startle modulation (PubMed:12089526). Interacts with CDH1 and CDH2 (By similarity). Interacts with ZNF639; recruits CTNNA2 to the nucleus (By similarity). Interacts with F-actin (By similarity). Expressed almost exclusively in the nervous system. The ratio of the two isoforms changes during development; isoform 1 is more abundant than isoform 2 in earlier embryonic stages, whereas isoform 2 is predominant in the adult stage. Expressed in the ventricular zone and in neurons of the developing cortical plate (at protein level). Expressed in migrating neurons of the external granule cell layer at 13.5 dpc while expression appears in the Purkinje cell layer at 17.5 dpc (at protein level). Expressed postnatally in Purkinje cells and hippocampus (at protein level). Mice generally die within 24 hours after birth. They display altered Purkinje cells migration, unstable synaptic junctions, defective ventricular architecture, impaired axon migration, reduced number of neurons in specific nuclei, and disordered laminar formation. The cdf (cerebellar deficient folia) mice are viable but are ataxic and have cerebellar hypoplasia associated with abnormal lobulation of the cerebellum. They also display defects in Purkinje cells positioning and in packing density and lamination. Fear conditioning and prepulse inhibition of the startle response are altered in cdf mice. Those phenotypes are associated with alteration of the Ctnna2 gene which results in the C-terminal truncation of the protein and are rescued by expression of a Ctnna2 transgene (isoform 2). Belongs to the vinculin/alpha-catenin family.