Chemoaffinity Revisited: Dscams, Protocadherins, and Neural Circuit Assembly

The chemoaffinity hypothesis for neural circuit assembly posits that axons and their targets bear matching molecular labels that endow neurons with unique identities and specify synapses between appropriate partners. Here, we focus on two intriguing candidates for fulfilling this role, Drosophila Dscams and vertebrate clustered protocadherins (Pcdhs). In each, a complex genomic locus encodes large numbers of neuronal transmembrane proteins with...