Objective To study the effect of soluble, refolded, recombinant extracellular domain of the human Fc gamma receptor Ⅱ a (huFcγRⅡa) on the binding of human IgG to cells. Methods Extra-cellular domain of the huFcγRⅡ a gene was amplified from recombinant plasmid pe3huR Ⅱ by PCR and then cloned into pET-28a vector. The recombinant plasmid pETshuR Ⅱ was transformed into E. coli BL21 (DE3) after identified by PCR and doubly digested. The inclusion bodies of fusion protein were extracted and purified by washing, dissolved in 6 mol/L guanidine buffer, and refolded by rapid dilution technique. The refolding protein activity was tested by ELISA and flow cytometry. Results Extraceilular domain of the huFcγRⅡa gene was successfully cloned into pET-28a. The results of SDS-PAGE showed that the molecular mass (Mr) of the expressed protein was 24.8 × 103, and the expression rate was 30%. The purity of recom-binant shuR Ⅱ was up to 90% after washing. ELISA showed that the recombinant shuR Ⅱ was able to bind human IgG in a dose dependent manner, shuRⅡ could competitively inhibit the binding of human IgG to huFcγRⅡa expressed on the surface of COS-7 cells by flow cytometry. Conclusion The results demon-strate that it is possible to obtain large quantities of recombinant shuR Ⅱ which has comparable binding prep-erties to those of the whole membrane bound huFcγR Ⅱ a.

OBJECTIVETo analyze the frequency of beta-fibrinogen (beta-Fg) gene -455G/A, -148C/T and 448G/A polymorphism, fibrinogen molecular reactivity and their association with plasma fibrinogen levels in health adults, myocardial infarction and cerebral infarction disease.

METHODSThe beta-Fg gene -455G/A, -148C/T and 448G/A polymorphisms were analyzed by restriction fragment length polymorphism (RFLP). Fibrinogen molecular reactivity was analyzed for the conversion kinetics of fibrinogen into fibrin by a computer assistant procedure. Plasma fibrinogen levels were determined by Clauss method.

RESULTSThe frequencies of -455A, -148T, 448A allele in health adults were 0.185, 0.194 and 0.192, in myocardial infarction disease 0.295, 0.318 and 0.307, in cerebral infarction disease 0.177, 0.193 and 0.182, respectively. The frequencies of -455A, -148T, 448A alleles in myocardial infarction disease were apparently higher than that of health adults. There were close linkage between -455G, -148C and 448G or -455A, -148T and 448A, the correspondence was over 98%. There are no differences in the plasma fibrinogen levels of the three polymorphisms in two genotype groups. The fibrinogen molecular reactivity was significantly increased in cardiocerebral vascular disease and related with plasma fibrinogen level.

CONCLUSIONThe three polymorphisms loci are strong linkage disequilibrium. There are no significant differences in the plasma fibrinogen levels of the three polymorphisms in two genotype groups. The frequencies of -455A, -148T, 448A alleles in myocardial infarction disease were apparently higher than that of health adults. It suggest that there was no association between beta-Fg gene -455G/A, -148C/T and 448G/A polymorphisms and plasma fibrinogen levels, but did in myocardial infarction disease. The fibrinogen molecular reactivity was significantly increased in cardiocerebral vascular disease and related with plasma fibrinogen level.

Adult ; Aged ; Aged, 80 and over ; Caenorhabditis elegans Proteins ; Cerebral Infarction ; genetics ; Female ; Fibrinogen ; analysis ; Gene Frequency ; Humans ; Linkage Disequilibrium ; Male ; Middle Aged ; Muscle Proteins ; genetics ; Myocardial Infarction ; genetics ; Polymorphism, Genetic