Rabbitts T H, Forster A, Milstein C P
Nucleic Acids Res. 1981 Sep 25;9(18):4509-24. doi: 10.1093/nar/9.18.4509.
Human immunoglobulin heavy chain constant region genes have been characterised in isolated clones. The human c mu gene comprises discrete domains for C mu 1, C mu 2, C mu 3 and C mu 4 + tp separated by short intervening sequences. The C delta gene has been located about 5 kb downstream of C mu 4. Furthermore, the coding segments for the membrane form of mu have been located 1.9 kb downstream of C mu 4. Tandemly repeated sequences implicated in the heavy chain class switch occur upstream of the C mu and the C gamma genes, but none were detected near the C delta gene. These tandem repeats are very homologous to those of mouse. Particularly common is the sequence G-A-G-C-T. These data suggest that the mu to gamma switch in humans involves DNA rearrangements of the CH-genes and subsequent deletion of DNA, but that the coexpression of C mu and C delta genes results from different mechanisms.
人类免疫球蛋白重链恒定区基因已在分离的克隆中得到表征。人类cμ基因包含Cμ1、Cμ2、Cμ3和Cμ4 + tp的离散结构域，由短间隔序列分隔。Cδ基因位于Cμ4下游约5 kb处。此外，μ膜形式的编码片段位于Cμ4下游1.9 kb处。与重链类转换相关的串联重复序列出现在Cμ和Cγ基因上游，但在Cδ基因附近未检测到。这些串联重复序列与小鼠的非常同源。特别常见的序列是G-A-G-C-T。这些数据表明，人类中μ到γ的转换涉及CH基因的DNA重排和随后的DNA缺失，但Cμ和Cδ基因的共表达是由不同机制导致的。
