Expression, Purification And Activitical Indentification Of Immunotolerance Related Molecular SHLA-G1

HLA-G is a non-classical MHC class I molecule involved in immunotolerance. It is selectively expressed on cytotrophoblasts at the maternal-feto interface,where it plays an important role in maternal tolerance of the semiallogenetic fetus.Recently,some reports showed that malignant melanoma cells exhibit a high level of HLA-G transcription and protein expression. Thus, they proposed that HLA-G may play a functional role in protecting tumor cells from NK destruction.This remains a highly constroversial area. In constrast to classical HLA-Ia genes,HLA-G has limited polymorphism's other HLA-Ib genes.To date,sixteen alleles have been described that give rise to only four productive proteins for HLA-G. The primary transcript of the HLA-G gene generates at least seven isoforms:four membrane-bound proteins(HLA-Gl,-G2,-G3,-G4)and three soluble proteins (HLA-G5,-G6,-G7).Although the capacity of the HLA-G molecules to inhibit NK cell lysis is well known,the recognization and interaction between HLA-G and NK cell reports remain to be determined.For this aim,we cloned the cDNA of HLA-G 1 from placenta,monocytes and liver cancer tissue of Chinese donors.We constructed prokaryotic expression plasmid(pGEXT-HLA-Gl),which can express truncated HLA-G,as a fusion protein with glutathione S-transferase(GST) in E.coli.after the process of the inclusion bodies lysis and renature, the fusion protein was purified on glutathion-sepharose beads. By the 5lGr assay, we can know the fusion protein GST-HLA-G1 inhibit the lytic activity of NK92 cell.