δ-Protocadherins: a gene family expressed differentially in the mouse brain

Phylogenetic analysis of protocadherin genes identified a new gene subfamily, the δ-protocadherins, containing several conserved motifs in their cytoplasmic domains. This subfamily can be further subdivided into two subgroups, named δ1-protocadherins (comprising protocadherin-1, -7, -9, and -11 or X/Y) and δ2-protocadherins (comprising protocadherin-8, -10, -17, -18, and -19). The members of the δ1-protocadherin subgroup were analyzed in greater detail here. They share a similar gene structure that results in the expression of multiple alternative transcripts. All members of this subgroup have at least one transcript that contains a binding site for protein phosphatase-1α. Like most classic cadherins, each of three δ1-protocadherins analyzed in this study by in situ hybridization showed a unique expression pattern that differed from the patterns of the other δ1-protocadherins. Together, these results suggest that the members of the δ1-protocadherin subgroup exercise tightly regulated functions in the development, regionalization, and functional differentiation of the mouse brain.