- Proteolytic fragments of Alzheimer's disease-associated presenilin 1 are present in synaptic organelles and growth cone membranes of rat brain. Beher, D., Elle, C., Underwood, J., Davis, J.B., Ward, R., Karran, E., Masters, C.L., Beyreuther, K., Multhaup, G. J. Neurochem. (1999)