Protocadherin-1, also known as Cadherin-like protein 1, Protocadherin-42 and PCDH1, belongs to the protocadherin subfamily within the cadherin superfamily. PCDH1 contains seven cadherin-like domains, a transmembrane region and a C-terminal cytoplasmic region. PCDH1 can be detected as early as embryonic day 9.5. In early embryogenesis, expression is especially prominent in blood vessels. The tight spatial and temporal regulation of Pcdh1 expression suggests that this protocadherin plays multiple roles not only during development but also in mature tissues and organs. In addition, protocadherin-1 is involved in cell-cell interaction processes and in neural cell adhesion.