Biologic and biochemic properties of recombinant platelet factor 4 demonstrate identity with the native protein

摘要: Platelet factor 4 (PF4) is a 70 amino acid protein released from the alpha-granules of platelets after activation. The exact biologic function this unknown. We have constructed an expression vector for recombinant PF4 (rPF4) in T7-based promoter pT7-7 to better study relationship between structure and function. was expressed Escherichia coli purified homogeneity by heparin-agarose affinity chromatography reverse-phase high-performance liquid chromatography. Purity confirmed immunoblot analysis sodium dodecyl sulfate-polyacrylamide gel electrophoresis, which resulted single component with molecular weight 8,000 daltons. composition sequence N-terminal 20 residues showed that rPF4 identical prepared human (hPF4), except initiating methionine residue. Immunoblots revealed hPF4 bound polyclonal anti-hPF4 equally well, while chemotaxis experiments demonstrated similar potencies as neutrophil attractants. Dose-dependent chemotactic responses competitive studies antiserum further demonstrate properties two species. In conclusion, our data show native appears immunologic, heparin-binding, properties. appear be entirely intrinsic not due, part, any contaminating protein. Furthermore, should prove useful construction forms investigate structure/function relationships biologically important