The clustered protocadherin (Pcdh) family is the largest subgroup of the cadherin superfamily. In mammals, the clustered Pcdh family consists of three gene clusters: Pcdh-alpha, Pcdh-beta, and Pcdh-gamma (Pcdhg) []. The genomic organisation of the human protocadherin gene clusters is remarkably similar to that of immunoglobulin and T-cell receptor genes. The extracellular and transmembrane domains of each protocadherin protein are encoded by an unusually large "variable"region exon, while the intracellular domains are encoded by three small "constant"region exons located downstream from a tandem array of variable region exons [, ]. The clustered Pcdh proteins are predominantly expressed in the brain []. Pcdh cluster genes may contribute to specifying the identity and diversity of individual neurons [].The 22 isoforms of the Pcdhg gene cluster are diversified into A-, B-, and C-types, and the C-type isoforms differ from all other clustered Pcdhs in sequence and expression. Mice lacking the three C-type isoforms (Pcdhgc3, Pcdhgc4, Pcdhgc5) display cellular and synaptic alterations resulting from neuronal apoptosis [].This entry represents protocadherin gamma-C3.
