Secretion kinetics of Alzheimer's amyloid beta-protein differs from secreted beta-amyloid precursor protein.

Amyloid beta-protein (A beta) and secreted beta-amyloid precursor protein (sAPP), derived from beta-amyloid precursor protein (APP), are normally released by cultured mammalian cells. We investigated by pulse-chase analysis the secretion kinetics of these two APP derivatives using mouse cholinergic SN49 cell lines stably transfected with mouse APP695 cDNA. After both A beta and sAPP peaked at about the second hour, sAPP decreased with a half-life of approximately 5 hours, but A beta remained almost unchanged for at least 14 hours. These results indicate that A beta is more stable than sAPP in the SN49 conditioned medium.