Ap-amyloid precursor protein

APP P-amyloid precursor protein 21q21 Dominant AP production (ApT AP AP ratioT)/aggregation... 

Strong evidence suggests that the main constituent of the plaque, P-amyloid peptide (AP), exerts a prominent role in the cause, initiation and progression of AD. Thus AD appears to arise from the abnormal deposition of a protein. Ap is derived from proteolytic cleavage of amyloid precursor protein (APP), an integral membrane protein. APP is cleaved by the sequential actions of three unique proteases, called a-, p-, and y-secretases. Each secretase cleaves at a unique site (see figure 8.7). 

Figure 8.7 Top Sequence of Api 3 and sites of secretase cleavage. y-Secretase has low specificity, cleaving the amyloid precursor protein (APP) anywhere between residues 39 to 43 of Ap. The transmembrane portion of APP is indicated. Bottom processing of amyloid precursor protein (APP) (A) Normal cleavage within AP region by a-secretase (B) pathogenic cleavage of APP by P- and y-secretase, liberating Ap, which can become incorporated into growing plaques. (Note AP = P-Amyloid Peptide)...

Beta-amyloid precursor proteins (/i-APPs) are normal components of the human brain and some other tissues. Proteolysis of these, presumably by serine proteases, generates a 39 to 42 amino acid-long peptide, oc-AP. In AD brains, / -AP aggregates into plaque, the hallmark of AD brains. Some of the... 

Ap is the principal constituent of senile plaques found in AD patients brains and as such has made it a key suspect in the search for causative agents of AD. Ap is a 39-43 residue peptide (Fig. 1) that is derived from the proteolytic cleavage of the amyloid precursor protein APP, a type I integral membrane protein. APP is processed by three proteases a-, P-, and... 

Sphingosylphosphorylcholine (SPC), a choline-containing sphingo-lipid, shows suppressive effect on Ap production in PC12 cells which stably express Swedish mutant of amyloid precursor protein... 

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