Koshland M E, Davis J J, Fujita N J
Proc Natl Acad Sci U S A. 1969 Aug;63(4):1274-81. doi: 10.1073/pnas.63.4.1274.
To determine the chemical basis for rabbit heavy chain allotypes, amino acid analyses were carried out on IgG and IgM antibodies isolated from rabbits which were homozygous a1 or a3 for the gamma chain locus and homozygous b4 for the light chain locus. The compositional differences between a1 and a3 IgM antibodies were found to be identical to those between their IgG counterparts. The identity of the allotypic amino acid replacements showed that the same genetic markers were present in the variable sequences of IgG and IgM heavy chains. Since the constant sequences of these heavy chains are controlled by different loci, these data demonstrated that rabbit heavy chains are coded by two separate germ-line genes, one producing the variable region and a second one of various genes producing the constant regions. The use of two antibodies, antiazophenylarsonate and antiazophenyl-beta-lactoside, permitted the compositions to be compared also on the basic of immunological specificity. The specificity amino acid replacements were found to be identical in the IgM and IgG heavy chains whether the two antibodies were isolated from and individual animal of a1 or a3 allotype. These results further support the conclusions of the allotype measurements that at least two genes code for the rabbit heavy chain.
为了确定兔重链同种异型的化学基础，对从γ链基因座纯合a1或a3且轻链基因座纯合b4的兔体内分离出的IgG和IgM抗体进行了氨基酸分析。发现a1和a3 IgM抗体之间的组成差异与其IgG对应物之间的差异相同。同种异型氨基酸替换的一致性表明，IgG和IgM重链的可变序列中存在相同的遗传标记。由于这些重链的恒定序列由不同的基因座控制，这些数据表明兔重链由两个独立的种系基因编码，一个产生可变区，另一个产生各种恒定区的基因。使用两种抗体，抗偶氮苯胂酸盐和抗偶氮苯-β-乳糖苷，也可以根据免疫特异性比较组成。无论这两种抗体是从a1或a3同种异型的单个动物中分离出来的，特异性氨基酸替换在IgM和IgG重链中都是相同的。这些结果进一步支持了同种异型测量的结论，即至少有两个基因编码兔重链。
