Faulmann E L, Otten R A, Barrett D J, Boyle M D
Department of Microbiology, Medical College of Ohio, Toledo 43699.
J Immunol Methods. 1989 Oct 24;123(2):269-81. doi: 10.1016/0022-1759(89)90231-7.
Protein G, a type III bacterial IgG Fc receptor isolated from certain group C or G streptococci, shows a wider range of species and subclass immunoglobulin reactivity than staphylococcal protein A and has been shown to be more useful than protein A for many immunochemical applications. Recently, two forms of wild type protein G and three forms of recombinant protein G have become commercially available. Each form of protein G was tested for reactivity with a variety of species of immunoglobulin and albumin. Additionally, one form of wild type protein G and two forms of the recombinant protein G were examined for their ability to stimulate in vitro proliferation of human peripheral blood leukocytes (PBL). Similar IgG species reactivity was observed for all forms of unlabeled protein G. By contrast, considerable variability in the relative IgG binding potentials of different protein G preparations was observed following radioiodination. Binding to human serum albumin was observed with one of the wild type protein G samples, however, the IgG binding activity of this protein was not affected by the presence of excess human serum albumin. In the human PBL proliferation assays, wild type protein G was weakly mitogenic and one form of recombinant protein G was shown to be a potent mitogen, while another form of recombinant protein G displayed no mitogenic potential. Differences in both functional and biological reactivities were observed among the various sources of protein G. These differences may lead to confusion if investigators consider all sources of protein G as a single entity with common properties.
蛋白G是一种从某些C组或G组链球菌中分离出的III型细菌IgG Fc受体，与葡萄球菌蛋白A相比，它对不同物种和亚类免疫球蛋白的反应范围更广，并且已被证明在许多免疫化学应用中比蛋白A更有用。最近，两种野生型蛋白G和三种重组蛋白G已上市销售。对每种形式的蛋白G与多种免疫球蛋白和白蛋白的反应性进行了测试。此外，检测了一种野生型蛋白G和两种重组蛋白G刺激人外周血白细胞（PBL）体外增殖的能力。所有形式的未标记蛋白G都观察到相似的IgG物种反应性。相比之下，放射性碘化后，不同蛋白G制剂的相对IgG结合潜力存在很大差异。在一种野生型蛋白G样品中观察到与人血清白蛋白的结合，然而，该蛋白的IgG结合活性不受过量人血清白蛋白存在的影响。在人PBL增殖试验中，野生型蛋白G有微弱的促有丝分裂作用，一种重组蛋白G被证明是一种有效的促有丝分裂原，而另一种重组蛋白G没有促有丝分裂潜力。在蛋白G的不同来源之间观察到功能和生物学反应性的差异。如果研究人员将蛋白G的所有来源视为具有共同特性的单一实体，这些差异可能会导致混淆。
