Induces KLC1 association with vesicles and functions as a cargo in axonal anterograde transport. Complex formation with APBA2 and APP, stabilizes APP metabolism and enhances APBA2-mediated suppression of beta-APP40 secretion, due to the retardation of intracellular APP maturation. In complex with APBA2 and C99, a C-terminal APP fragment, abolishes C99 interaction with PSEN1 and thus APP C99 cleavage by gamma-secretase, most probably through stabilization of the direct interaction between APBA2 and APP. As intracellular fragment AlcICD, suppresses APBB1-dependent transactivation stimulated by APP C-terminal intracellular fragment (AICD), most probably by competing with AICD for APBB1-binding. May modulate calcium-mediated postsynaptic signals (By similarity). Directly interacts with APBA2. Forms a tripartite complex with APBA2 and APP. The CTF1 chain interacts with PSEN1. The intracellular fragment AlcICD interacts with APBB1; this interaction stabilizes AlcICD metabolism. Interacts with KLC1 and APBB1 (By similarity). Neurite tips. Localized in the postsynaptic membrane of both excitatory and inhibitory synapses. The AlcICD fragment is translocated to the nucleus upon interaction with APBB1 (By similarity). Preferentially expressed in the retina and brain. The cytoplasmic domain is involved in interaction with APBA2, as well as the binding of synaptic Ca(2+). Proteolytically processed under normal cellular conditions. A primary zeta-cleavage generates a large extracellular (soluble) N-terminal domain (sAlc) and a short C-terminal transmembrane fragment (CTF1). A secondary cleavage catalyzed by presenilin gamma-secretase within the transmembrane domain releases the beta-Alc-alpha chain in the extracellular milieu and produces an intracellular fragment (AlcICD). Beta-Alc-alpha secretion is largely dependent upon PSEN1 and PSEN2. This processing is strongly suppressed in the tripartite complex formed with APBA2 and APP, which seems to prevent the association with PSEN1 (By similarity).