BICC1, also known as protein bicaudal C homolog 1, is a 974 amino acid protein that belongs to the BICC family. BICC1 is considered a putative RNA-binding protein and may be involved in regulating gene expression during embryonic development by modulating protein translation. Existing as two alternatively spliced isoforms, BICC1 contains two KH domains as well as one SAM (sterile α motif) domain. Both BICC1 isoforms are widely expressed in normal tissues and are found in all brain regions including cerebral cortex, hippocampus and midbrain, although BICC1 isoform 1 is more highly expressed than isoform 2, particularly in nerve tissue. BICC1 can uncouple dishevelled-2 (Dvl-2) signaling from the canonical Wnt pathway in a SAM domain dependent manner, suggesting that the different BICC1 isoforms may play varying biological roles. Genetic variants in BICC1 may be involved in recurrent unipolar major depression. Acts as a negative regulator of Wnt signaling. May be involved in regulating gene expression during embryonic development.