Has a critical role in neuronal development, particularly in the formation and/or maintenance of dendritic spines and synapses (PubMed:25807484). Involved in the regulation of Wnt signaling (PubMed:25807484). It probably acts on beta-catenin turnover, facilitating beta-catenin interaction with GSK3B, phosphorylation, ubiquitination and degradation (By similarity). Functions as a transcriptional activator when bound to ZBTB33 (By similarity). May be involved in neuronal cell adhesion and tissue morphogenesis and integrity by regulating adhesion molecules. Binds to E-cadherin at a juxtamembrane site within the cytoplasmic domain (By similarity). Interacts with PDZD2 (By similarity). Interacts with ZBTB33 (By similarity). Binds to PSEN1 (PubMed:10037471) (PubMed:10208590) (PubMed:9223106). Interacts with ARHGEF28 (PubMed:17993462). Interacts (via the extreme C-terminus) with FRMPD2 (via the PDZ 2 domain) (PubMed:19706687). Interacts with CDK5 (By similarity). Interacts with CTNNB1 (PubMed:25807484). Interacts with GSK3A and GSK3B (PubMed:19706605). Interacts with DNM2 (PubMed:22022388). Interacts with CCDC85B (PubMed:25009281). Additional isoforms seem to exist. Expressed in brain; highest expression is observed in fetal brain (PubMed:25807484). O-glycosylated. Phosphorylated by CDK5 (By similarity). Phosphorylated by GSK3B (PubMed:19706605). Defects in CTNND2, including deleterious missense and copy number variants (CNVs) are involved in autism, a complex multifactorial, pervasive developmental disorder characterized by impairments in reciprocal social interaction and communication, restricted and stereotyped patterns of interests and activities, and the presence of developmental abnormalities by 3 years of age. Most individuals with autism also manifest moderate intellectual disability. Belongs to the beta-catenin family. Truncated N-terminus.