The α, β, δ, and γ -catenins are proteins that bind to the highly conserved, intracellular cytoplasmic tail of E-cadherin. Together, the catenin/cadherin complexes play an important role mediating cellular adhesion. α-catenin, a 102 kDa protein, interacts with E-cadherin associated protein, and also associates with other members of the cadherin family, such as N-cadherin and P-cadherin. The 92 kDa β-catenin associates with the cytoplasmic portion of E-cadherin, which is necessary for the function of E-cadherin as an adhesion molecule. β-catenin also complexes with the tumor suppressor protein APC. δ-catenin interacts with Presenilin 1 and is expressed in the brain. The gene encoding δ-catenin maps to human chromosome 5p15.2. A hemizygous loss of the gene encoding δ-catenin leads to the mental retardation associated with Cri-du-Chat syndrome. γ-catenin, also known as plakoglobin, is an 80-88 kDa protein that binds α-catenin and N-cadherin. In addition, the transmembrane phosphatase PTPm associates with catenin/cadherin complexes and may regulate complex signaling.