Kurosawa Y, Tonegawa S
J Exp Med. 1982 Jan 1;155(1):201-18. doi: 10.1084/jem.155.1.201.
We have identified, cloned, and sequenced eight different DNA segments encoding the diversity (D) regions of mouse immunoglobulin heavy-chain genes. Like the two D segments previously characterized (16, 17), all eight D segments are flanked by characteristic heptamers and nonamers separated by 12-bp spacers. These 10 D segments, and several more D segments identified but not yet sequenced, can be classified into three families based on the extent of sequence homology. The SP2 family consists of nine highly homologous D segments that are all 17-bp long and clustered in a chromosomal region of approximately 60 kb. The FL16 family consists of up to four D segments, two of which were mapped in the 5' end region of the SP2-D cluster. The two FL16D segments are 23 and 17 bp long. The third, the Q52 family, is a single-member family of the 10-bp-long DQ52, located 700 bp 5' to the JH cluster. We argue that the D-region sequences of the majority of heavy chain genes arise from these germline D segments by various somatic mechanisms, including joining of multiple D segments. We present a specific model of D-D joining that does not violate the 12/23-bp spacer rule.
我们已鉴定、克隆并测序了八个不同的编码小鼠免疫球蛋白重链基因多样性（D）区的DNA片段。与先前鉴定的两个D片段（16, 17）一样，所有八个D片段两侧均为特征性的七聚体和九聚体，中间间隔12个碱基对的间隔序列。这10个D片段，以及另外几个已鉴定但尚未测序的D片段，可根据序列同源程度分为三个家族。SP2家族由九个高度同源的D片段组成，它们均为17个碱基对长，聚集在大约60 kb的染色体区域。FL16家族由多达四个D片段组成，其中两个定位于SP2-D簇的5'端区域。这两个FL16 D片段分别为23个和17个碱基对长。第三个家族，即Q52家族，是一个单成员家族，由10个碱基对长的DQ52组成，位于JH簇5'端700个碱基对处。我们认为，大多数重链基因的D区序列是通过各种体细胞机制从这些种系D片段产生的，包括多个D片段的连接。我们提出了一种不违反12/23碱基对间隔规则的D-D连接的具体模型。
