Hsu E, Flajnik M F, Du Pasquier L
J Immunol. 1985 Sep;135(3):1998-2004.
A new class of immunoglobulin (IgX) has been found in the South African frog, Xenopus laevis, and other related species. IgX can be immunoprecipitated by monoclonal antibodies directed against determinants found on Xenopus light chain, or on variable regions of heavy chains. Reagents specific for the heavy chain of IgM or the amphibian IgG equivalent, IgY, failed to react with IgX. IgX, which exists in serum as a polymer, is composed of subunits of disulfide-bonded heavy chains of 80,000 daltons and light chains of 25,000 to 29,000 daltons. Like mu, the heavy chain of IgX carries a large amount of asparagine-linked carbohydrate, but the partial peptide maps of the two are different. Although the concentration of IgX varies greatly in the serum of individual frogs, it is always secreted in cultures of cells from the spleen and intestinal mucosae.
在南非爪蟾及其他相关物种中发现了一类新的免疫球蛋白（IgX）。IgX可被针对爪蟾轻链或重链可变区上的决定簇的单克隆抗体免疫沉淀。针对IgM重链或两栖动物等效的IgG（即IgY）的特异性试剂不能与IgX发生反应。IgX以聚合物形式存在于血清中，由二硫键连接的80,000道尔顿重链亚基和25,000至29,000道尔顿轻链亚基组成。与IgM的重链μ一样，IgX的重链携带大量天冬酰胺连接的碳水化合物，但两者的部分肽图不同。尽管个体青蛙血清中IgX的浓度差异很大，但它总是在脾脏和肠黏膜细胞培养物中分泌。
