Kappes D J, Strominger J L
Immunogenetics. 1986;24(1):1-7. doi: 10.1007/BF00372291.
The class II major histocompatibility complex antigens are cell-surface heterodimers consisting of an alpha and a beta chain. Cosmid cloning has shown that the three families of class II antigens, DR, DQ, and DP, are encoded within the HLA-D region of chromosome 6 as a series of discrete gene clusters. The DP cluster contains two pairs of alpha and beta genes, one of which encodes the biochemically-defined DP antigen. In order to assess whether the other two genes, SX alpha and SX beta, are also expressed, potential coding regions have been subcloned and sequenced. The SX3 beta gene is shown to contain regions closely homologous to all six exons of DP beta. A 1 bp deletion in the beta 2 exon, also observed for the SX4 beta allele, causes a translational frameshift, suggesting that SX beta is a pseudogene. However, all the other exons, as well as their splice sites and the putative promoter region, appear to be intact.
II类主要组织相容性复合体抗原是由一条α链和一条β链组成的细胞表面异二聚体。黏粒克隆显示，II类抗原的三个家族，即DR、DQ和DP，在6号染色体的HLA-D区域内作为一系列离散的基因簇进行编码。DP簇包含两对α和β基因，其中一对编码生化定义的DP抗原。为了评估另外两个基因SXα和SXβ是否也表达，已对潜在的编码区域进行亚克隆和测序。结果显示，SX3β基因包含与DPβ的所有六个外显子紧密同源的区域。在SX4β等位基因中也观察到β2外显子中有1个碱基缺失，导致翻译移码，这表明SXβ是一个假基因。然而，所有其他外显子及其剪接位点以及假定的启动子区域似乎都是完整的。
