APP and Alzheimer disease: However, the presynaptic function of APP described here , together with evidence that the other familial Alzheimer’s proteins PS1 and PS2 regulate glutamate release in mature neurons by a presynaptic mechanism (Fogel et al., 2014, Wu et al., 2013, Xia et al., 2015, Zhang et al., 2009), support the possibility that deficits in neurotransmitter release represents a convergent mechanism involved in AD.