sAPPα is the extracellular protein that is released from the transmembrane amyloid precursor protein (APP) upon cleavage with α-secretase. Cleavage of APP with α-secretase precludes formation of Aβ peptides, as the cleavage site is within the Aβ sequence. The sAPPα Base Kit provides basic components for the quantitative determination of both natural and recombinant human soluble amyloid precursor protein alpha (sAPPα) in cerebrospinal fluid, brain homogenates, and tissue culture supernatants. Base kits generally include only MSD plates coated with the capture antibody, SULFO-TAG-labeled antibody, and MSD proprietary read buffer. (See product insert for a list of kit components). Base kits are most commonly used for high-throughput screening and assay development.