Beta-amyloid (Abeta) deposition in the brain is the hallmark of Alzheimer's Disease (AD). To initiate Ab formation, beta-secretase cleaves APP at the N-terminus of Ab to release APPsb (~100kD soluble NT-fragment), and C99, a 12-kD CT membrane fragment. Alternatively, alpha-secretase cleaves within the Ab to prevent the formation of Ab. Cleavage by a-secretase produces a soluble N-terminal fragment, APPsa, and a 10-kD membrane C-terminal fragment, C83. Both C99 and C83 can be further cleaved by gamma-secretase releasing Ab and a nonpathogenic p3 peptide, respectively.
Recently, BACE (Beta-site APP Cleaving Enzyme) has been identified as b-secretase. BACE belongs to the family of Aspartyl proteases (Asp) also known as Memapsins. At least four related Asps, located on chromosome IV and X, have been cloned (Asp1, Asp2, Asp3, and Asp4). Human BACE/Asp2/Memapsin2, located on chromosome 11, is a transmembrane protein of 501 aa (signal peptide 1-21 aa, a proprotein domain 22-45 aa, 1 TM domain near the CT, and a short cytoplasmic CT- tail of 24 aa; mature protein 46-460 aa). The lumenal portion of BACE has two active site motifs at 93 aa and 289 aa with signature sequence of aspartic proteases. Rat and mouse BACE (501 aa) are 96% identical with human BACE. BACE expression was most prominent in most areas of the rat brain and pancreas. It has been localized in the compartments of the secretory pathways.
Applications
Suitable for use in ELISA, Western Blotting. Other applications not tested.
Recommended Dilution
Western Blot: 1:1000-1:5000 for neat serum and 1-10ug/ml for affinity pure using ECL. BACE is approx 70kD, greater than the theoretical size of ~51kD, due to glycosylation. ELISA: 1:10,000-1:100,000 using 50-100ng of control peptide/well.
See corresponding control antigen B0002-92.
Optimal dilutions to be determined by the researcher.
Storage and Stability
May be stored at 4°C for short-term only. For long-term storage, store at -20°C. Aliquots are stable for at least 12 months at -20°C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.
Immunogen
A 20 aa peptide near the CT of human BACE2/Asp1 (1) conjugated to KLH
Form
Supplied as a liquid, neat serum, 40% glycerol.
Specificity
The human peptide sequence has high degree of homology (94%) with mouse and rat BACE/Asp2. No significant sequence homology exists with BACE2/Aps1, a homolog of BACE, or other Asps. Antibody crossreactivity in various species is not established. Control peptides, because of their low MW (<3kD), are not suitable for Western. It should be used for ELISA or antibody blocking to confirm antibody specificity
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