Protocadherins are a large family of cadherin-like cell adhesion proteins that are involved in the establishment and maintenance of neuronal connections in the brain. There are three protocadherin gene clusters, designated alpha, beta and gamma, all of which contain multiple tandemly arranged genes. PCDHA5 (Protocadherin alpha-5) is one of fifteen members of the protocadherin alpha protein family that is expressed in neurons. PCDHA5 is a 936 amino acid single-pass type I membrane protein containing 6 cadherin domains. Localized to the cell membrane, PCDHA5 functions as a calcium-dependent cell-adhesion protein that is present in synaptic junctions and is essential to the establishment and maintenance of certain cell-cell interactions. PCDHA5 is expressed as 3 isoforms produced by alternative splicing.