Pregnancy-associated plasma protein-A (PAPP-A, Insulin-like growth factor binding protein-4 protease, PAPP-A-proMBP complex) is a large heterotetrameric glycoprotein of approximately 500kD, which was first discovered in serum from pregnant women. The hetreotetramer consists of two PAPP-A subunits and two proMBP subunits. Low maternal serum levels of PAPP-A in first trimester biochemical screening is used as a marker of Down’s syndrome (trisomy 21).
Applications
Suitable for use in ELISA, Western Blot and Immunohistochemistry. Other applications not tested.
Recommended Dilution
ELISA: 1:8000. In sandwich ELISA the optimal combination was P6000-80D as coating and biotinylated clone 6F173 as detection. Western Blot: Detects only unreduced PAPP-A. Immunohistochemistry: Gives the strongest signal compared to P6000-80D. Optimal dilutions to be determined by the researcher.
Storage and Stability
May be stored at 4°C for short-term only. Aliquot to avoid repeated freezing and thawing. Store at -20°C. Aliquots are stable for 12 months after receipt. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap.
Immunogen
Purified human PAPP-A
Form
Supplied as a liquid in PBS, pH 7.4, 15mM sodium azide.
Purity
Purified by Protein G affinity chromatography from culture supernatant.
Specificity
Recognizes native human PAPP-A. Heat and SDS denatured PAPP-A is also recognized, but not acid-treated PAPP-A. The epitope is different from that of P6000-80D and is located on the PAPP-A subunit of the heterotetramer.
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