Peering into proteolysis with presenilins.

Presenilins were originally identified because they cause a neurodegenerative disease, but the impact of these proteins on the neuron appears to extend beyond neurodegeneration and into fundamental concepts of cell biology and development. Presenilins were identified as a result of the steady march of molecular genetics which first lead to identification of loci on chromosomes 1 and 14 that segregated with the phenotype of early onset familial Alzheimer Disease (AD), and then to discovery of the genes coding for PS1 and PS2.