Marchalonis J J, Atwell J L, Goding J W
Immunology. 1978 Jan;34(1):97-103.
7S immunoglobulins of a monotreme mammal, the echidna , bind to A protein coupled to an insoluble matrix. This binding supports the homology between the previously described echidna IgG and IgG molecules of higher mammals and provides a rapid, simple method for the isolation of this protein from echidna serum. In addition, another echidna 7S immunoglobulin became bound to protein A-Sepharose. The major protein A-binding immunoglobulin has a slow electrophoretic mobility and possesses a heavy chain comparable in mass to typical mammalian γ chains (52,000 daltons). We suggest the designation IgG2 for this immunoglobulin. The minor protein A-binding immunoglobulin is electrophoretically faster than IgG2 and can be resolved from the former by gradient elution from DEAE-Biogel. We propose the nomenclature IgG1 for this molecule although we cannot discount the possibility that it might represent another main class such as IgA. The γ1 heavy chain is distinguishable from the γ2 chain on polyacrylamide gel electrophoresis in sodium dodecylsulphate containing buffers. The γ1 chain possesses a nominal mass of 61,000 daltons. The intact molecule has an apparent mass of 177,000 Daltons and comprises two pairs of light and heavy chains.
单孔目哺乳动物针鼹的7S免疫球蛋白与偶联于不溶性基质的A蛋白结合。这种结合支持了先前描述的针鼹IgG与高等哺乳动物IgG分子之间的同源性，并提供了一种从针鼹血清中分离该蛋白的快速、简单方法。此外，另一种针鼹7S免疫球蛋白也与蛋白A-琼脂糖结合。主要的蛋白A结合免疫球蛋白电泳迁移率较慢，其重链质量与典型的哺乳动物γ链（52,000道尔顿）相当。我们建议将这种免疫球蛋白命名为IgG2。次要的蛋白A结合免疫球蛋白电泳速度比IgG2快，可通过从DEAE-琼脂糖凝胶上进行梯度洗脱与前者分离。尽管我们不能排除它可能代表另一个主要类别如IgA的可能性，但我们建议将该分子命名为IgG1。在含十二烷基硫酸钠的缓冲液中进行聚丙烯酰胺凝胶电泳时，γ1重链可与γ2链区分开来。γ1链的标称质量为61,000道尔顿。完整分子的表观质量为177,000道尔顿，由两对轻链和重链组成。
