Cloning And Expression Of Mouse Apolipoprotein M Gene

Apolipoprotein M(ApoM) is a recently discovered human apolipoprotein. Among the various lipoprotein subclasses, ApoM is associated mainly with high density lipoprotein(HDL) in human plasma, but is also detected in triglyceride-rich lipoproteins(TGRLP) and low-density lipoprotein(LDL). In all of these lipoproteins, ApoM appeared to be a minor component as compared with the major apolipoproteins. The ApoM gene is found in all mammalian genomes. It is prominent in both liver and kidney but not in other organs. The synthesis of ApoM in liver may be associated with the production of HDL. The ApoM gene is located in the major histocompatibility complex Class III region on chromosome 6.The functions of ApoM are to be determined. Apart from the hypothetical involvement in synthesis of HDL, it is possible that ApoM severs a specific function in the metabolism and transfer of cholesterol. ApoM has the characteristics of a membrane intergral protein, and it is possible that ApoM is incorporated into the lipoptein particles together with phospholipids from the endoplasmic reticulum and then secreted to plasma. ApoM may transport hydrophobic low molecular weight compounds.To search for functions of ApoM gene, we clone and express mouse ApoM gene efficiently in the study. The total RNA was extracted from mouse liver, the complete cDNA of normal adult mouse ApoM was amplified by RT-PCR and recombined into pGEX-KG plasmid, then it was transformed into the competent expressive cells of E. coli BL21. After induced with IPTG, bacteria protein was collected for SDS-PAGE identification. The sequence of cloned mouse ApoM gene was identified with the reported one. Expressed fusion protein existed in the form of inclusion body. The protein band was 54 kDa appeared on SDS-GAGE gel. The mouse ApoM was cloned successfully and expressed efficiently in E. coli BL21 which create a favourable condition for preparation of anti- ApoM antidody.