Description
RP1-Presenilin-2 is a rabbit polyclonal antibody made to the aspartic proteinase presenilin-2. The antibody is made to a synthetic peptide based on the Amino-Terminal Fragment of human presenilin-2. The antibody has been peptide-affinity purified, concentrated to 1.0 mg/ml, with the addition of 0.05% sodium azide as preservative and 50% glycerol as cryoprotectant.
Use
Presenilin-2 (gamma secretase-2) is a multi-pass transmembrane aspartic proteinase known principally for its role in Alzheimer's disease. The identification of presenilin-2 as an aspartic protease was an epic scientific controversy. The protein was identified by linkage analysis of Alzheimers's patients, and a large family of mutations was discovered. Most of the mutations are thought to induce a loss of function which decreases the proteinase activity and yields a buildup of the A-beta fragment of amyloid plaque protein. The controversy revolved around the hypothesis that the cleavage occurred within the membrane, and that the catalytic residues were aspartic acids. This catalytic mechanism is well studied in other aspartic proteinases such as pepsin-A, but the reaction requires an active water molecule to act as the scissile agent, and the membrane is considered a hydrophobic environment. Also the fact that the domain structure looked so different than the more classical digestive aspartic proteinases made it difficult to map out the relationship. The discovery of other similar proteinases (tripeptidyl peptidase, signal peptidase, rhomboid proteases) made structural models easier, as did the discovery that mutations of the aspartic acids abolished proteinase activity. Presenilin-2 forms a proteosome-like complex with nicastrin, Aph-1, and Pen-2, and somehow this complex works to cleave within the membrane, or perturb the substrate outside of the membrane. Presenilin-2 is itself cleaved within the cytoplasmic loop into 2 fragments, the N-terminal and C-terminal fragments, and that this cleavage is apparently required for phosphorylation of presenilin-1 (but not PS2) and its enzymatic activity. Presenilin-2 is thought to be mainly localized to the ER membrane, where the first 87 amino acids are presented to the cytoplasm, followed by six tight passes through the membrane, then another 118 residues forming the cytoplasmic loop, then another 2 passes through the membrane. This model is evolving, since there is at present no crystal structure, and the complex with the partner proteins likely changes conformations. In addition to cleaving amyloid plaque protein, presenilin-2 is thought to cleave notch, and important developmental protein, and knockouts of presenilin-2 are lethal at embryonic stages presumably because of the failure to cleave notch. A number of other substrates have been identified for presenilin-2. Peresenilin-1 shares 65% overall identity at the amino acid level with presenilin-2, but most of the differences are in the cytoplasmic domains (the aminoterminus and the cytoplasmic loop). Homology is high for the transmembrane sections. A recommended starting concentration for Western blots is 1:1,000 when using colorimetric substrates such as BCIP/NBT, and 1:5,000 for chemiluminescent substrates. Higher concentrations of antibody may be needed for samples from more distantly related species. FOR RESEARCH USE ONLY; NOT FOR USE IN HUMANS.
Storage
The undiluted antibody solution is stable for 12 months at -20C.
Description
RP2-Presenilin-2 is a rabbit polyclonal antibody made to the aspartic proteinase presenilin-2. The antibody is made to a synthetic peptide based on the Carboxy-Terminal Fragment of human presenilin-2. The antibody has been peptide-affinity purified, concentrated to 1.0 mg/ml, with the addition of 0.05% sodium azide as preservative and 50% glycerol as cryoprotectant.
Use
Presenilin-2 (gamma secretase-2) is a multi-pass transmembrane aspartic proteinase known principally for its role in Alzheimer's disease. The identification of presenilin-2 as an aspartic protease was an epic scientific controversy. The protein was identified by linkage analysis of Alzheimers's patients, and a large family of mutations was discovered. Most of the mutations are thought to induce a loss of function which decreases the proteinase activity and yields a buildup of the A-beta fragment of amyloid plaque protein. The controversy revolved around the hypothesis that the cleavage occurred within the membrane, and that the catalytic residues were aspartic acids. This catalytic mechanism is well studied in other aspartic proteinases such as pepsin-A, but the reaction requires an active water molecule to act as the scissile agent, and the membrane is considered a hydrophobic environment. Also the fact that the domain structure looked so different than the more classical digestive aspartic proteinases made it difficult to map out the relationship. The discovery of other similar proteinases (tripeptidyl peptidase, signal peptidase, rhomboid proteases) made structural models easier, as did the discovery that mutations of the aspartic acids abolished proteinase activity. Presenilin-2 forms a proteosome-like complex with nicastrin, Aph-1, and Pen-2, and somehow this complex works to cleave within the membrane, or perturb the substrate outside of the membrane. Presenilin-2 is itself cleaved within the cytoplasmic loop into 2 fragments, the N-terminal and C-terminal fragments, and that this cleavage is apparently required for phosphorylation of presenilin-1 (but not PS2) and its enzymatic activity. Presenilin-2 is thought to be mainly localized to the ER membrane, where the first 87 amino acids are presented to the cytoplasm, followed by six tight passes through the membrane, then another 118 residues forming the cytoplasmic loop, then another 2 passes through the membrane. This model is evolving, since there is at present no crystal structure, and the complex with the partner proteins likely changes conformations. In addition to cleaving amyloid plaque protein, presenilin-2 is thought to cleave notch, and important developmental protein, and knockouts of presenilin-2 are lethal at embryonic stages presumably because of the failure to cleave notch. A number of other substrates have been identified for presenilin-2. Peresenilin-1 shares 65% overall identity at the amino acid level with presenilin-2, but most of the differences are in the cytoplasmic domains (the aminoterminus and the cytoplasmic loop). Homology is high for the transmembrane sections. A recommended starting concentration for Western blots is 1:1,000 when using colorimetric substrates such as BCIP/NBT, and 1:5,000 for chemiluminescent substrates. Higher concentrations of antibody may be needed for samples from more distantly related species. FOR RESEARCH USE ONLY; NOT FOR USE IN HUMANS.
Storage
The undiluted antibody solution is stable for 12 months at -20C.
