The high-density lipoprotein (High-density lipoprotein, HDL) is an important class of plasma lipoproteins, it participates in reverse cholesterol transport (Reverse cholesterol transport, RCT), extrahepatic cells and tissues excess cholesterol transport to the liver,and to convert and clear, and thus has anti-atherosclerotic role. APOA1(apolipoprotein A-I) is the major apolipoprotein in HDL, and its absence or reduction caused by the reduction of plasma HDL, resulting in the increase of coronary heart disease incidence. Studies have shown that APOA1 protein also has antioxidant, anticoagulant and anti-inflammatory effects, as well as regulating the expression of cell adhesion molecule-mediated intracellular signal transduction function. These features it has great significance to the protection of human arterial wall. Therefore, APOA1 has increasingly become the focus of lipid metabolism. In addition, study found that the liver cell surface APOA1 and HDL high-affinity receptors, and therefore free APOA1 and HDL with liver targeting characteristics of this important feature makes the APOA1 in the targeted drug research good application prospects.
In vivo, APOA1 is mainly synthesized by the liver cells and intestinal cells, the intracellular synthesis of APOA1 exists in the form of the precursor protein of 267 amino acids, the move of the precursor protein to the cell membrane and secreted into the extracellular secretion process The N-terminal 18 amino acid signal peptide (pre sequence) is removed. Secretion to the plasma APOA1 protein in the original protein (proAPOA1), in addition to its amino acid sequence of the mature protein, N-terminal also comes with six amino acid sequence of the pro. In plasma, pro sequenceColumn is an unknown metalloproteinase removed, the final form containing 243 amino acids of the mature APOA1. louis et al pro sequence is not necessary for intracellular processing, removal pm sequence does not affect the correct cutting of the signal peptide, but will slow down the rate of secretion of APOA1 work. Study proAPOA1 constitute HDL function, mature APOA1 protein can better promote the t3-HDL in reverse cholesterol transport process to a The conversion of HDL contribute to the play of APOA1 function. To date, there are a lot of restructuring of the expression of human APOA1 protein is reported that the most common application prokaryotic expression system.However, in Escherichia coli of APOA1 mRNA is extremely unstable, the expression of the mature protein is also susceptible to degradation, usually in the form of fusion protein expression, lack of maturity of APOA1. Researchers selected in Chinese hamster ovary cells expressing recombinant human APOA1, expression levels of up to 20 ~ g / mL. The baculovirus expression system has several advantages, such as high expression levels, a series of post-translational processing and modification of the recombinant protein.