• Purity

  >95%, by SDS-PAGE under reducing conditions and visualized by silver stain

• Endotoxin Level

  <0.10 EU per 1 μg of the protein by the LAL method.  

• Activity

  Measured by its binding ability in a functional ELISA. When Recombinant Human Apolipoprotein A‑I/ApoA1 is immobilized at 5 µg/mL (100 µL/well), the concentration of Recombinant Human SR‑AI/MSR (Catalog # ) that produces 50% of the optimal binding response is approximately 0.5‑2.5 µg/mL.

• Source

  E. coli-derived Asp25-Gln267, with an N-terminal Met and 6-His tag

• Accession #

• N-terminal Sequence    
  Analysis

  Met-His

• Predicted Molecular Mass

  29 kDa

• SDS-PAGE

  27 kDa, reducing condiitons

Background: Apolipoprotein A-I/ApoA1

Apolipoprotein A1 (ApoA1) is a 28 kDa glycoprotein that is the major protein component of high density lipoprotein (HDL) particles. HDL particles play a central role in the reverse transport of cholesterol from peripheral tissues to the liver. HDL is known as “good cholesterol” due to its ability to facilitate the removal of cholesterol from macrophage foam cells in atherosclerotic plaques and thereby retard the progression of disease (1, 2). ApoA1 is secreted from hepatocytes with variable amounts of lipidation (3). Disc‑like HDL particles increase in size and adopt a spherical shape as they are loaded with additional lipids and cholesterol by ABC family transporters (4, 5). HDL particle interaction with lipid‑supplying cells is mediated by ApoA1 binding to the scavenger receptor SR‑A1 (6). HDL particles are further modified by the circulating enzymes LCAT (which converts cholesterol to cholesteryl esters), CETP (which transfers cholesteryl esters to LDL/VLDL particles), and PLTP (which transfers phospholipids from HDL to LDL/VLDL particles) (2). Upon HDL particle return to the liver, ApoA1 binds to the scavenger receptor SR‑B1 and the beta chain of ATP synthase on hepatocytes (7, 8). Hepatocytes internalize the particles and pass the cholesterol into bile for excretion. Polymorphisms of ApoA1 are associated with dysregulation of HDL levels and cholesterol homeostasis (1, 9). ApoA1 is catabolized in the kidney following its binding to Cubulin on renal proximal tubule epithelial cells (10). ApoA1, either as a free molecule or in lipidated particulate form, induces the release of insulin from pancreatic islets in a process that is dependent on ABCA1 and SR‑B1 (11). Mature human ApoA1 shares 65% and 62% aa sequence identity with mouse and rat ApoA1, respectively.

• References:

1. Obici, L. et al. (2006) Amyloid 13:191.

2. Annema, W. and U.J.F. Tietge (2012) Nutr. Metab. 9:25.

3. Chisholm, J.W. et al. (2002) J. Lipid Res. 43:36.

4. Wang, N. et al. (2004) Proc. Natl. Acad. Sci. USA 101:9774.

5. Kiss, R.S. et al. (2003) J. Biol. Chem. 278:10119.

6. Neyen, C. et al. (2009) Biochemistry 48:11858.

7. Williams, D.L. et al. (2000) J. Biol. Chem. 275:18897.

8. Martinez, L.O. et al. (2003) Nature 421:75.

9. Cohen, J.C. et al. (2004) Science 305:869.

10. Kozyraki, R. et al. (1999) Nat. Med. 5:656.

11. Fryirs, M.A. et al. (2010) Arterioscler. Thromb. Vasc. Biol. 30:1642.

• Entrez Gene IDs:

  335 (Human); 11806 (Mouse); 25081 (Rat)

• Alternate Names:

  Alp-1; APOA1; Apo-AI; apoA-I; Apolipoprotein A1; Apolipoprotein AI; Apolipoprotein A-I; Brp-14; Ltw-1; Lvtw-1; MGC117399; Sep-1; Sep-2