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. The protocadherein gamma cluster consists of three subfamilies (A, B and C). As a member of the gamma subfamily B, PCDHGB1 (Protocadherin gamma B1) is a 927 amino acid protein that is one of 22 proteins encoded by the protocadherin gamma cluster. Typical of gamma protocadherins, PCDHGB1 contains six cadherin motifs and is a type I transmembrane receptor expressed in the central nervous system. With localization to synapses, members of the gamma cluster of protocadherins are essential for neuronal survival. There are two isoforms of PCDHGB1 that are produced as a result of alternative splicing events.