Pargent W, Meindl A, Thiebe R, Mitzel S, Zachau H G
Institut für Physiologische Chemie der Universität München, München, FRG.
Eur J Immunol. 1991 Aug;21(8):1821-7. doi: 10.1002/eji.1830210807.
Two large regions of the human immunoglobulin kappa locus, the so-called O regions, have been characterized on cosmid and phage lambda clones. The two regions are very similar but not identical duplicates belonging to the C kappa proximal (p) and the distal (d) copies of the kappa locus. The Op and Od regions comprise contigs of 90 and 120 kb, respectively, and contain 20 V kappa genes and pseudogenes which have been sequenced. Three pairs of V kappa genes were found to be practically identical in the duplicates while allotypic differences, at least for two of the genes, are considerable. The similarities between the duplicate genes may be related to the fact that the two copies of the kappa locus are arranged in a palindrome-like fashion with the 5' sides of the O regions pointing towards each other (C kappa J kappa B Lp Ap Op-Od Ad Ld). This may have contributed to equalizing the sequences. Beyond Op and Od no further V kappa genes were found within about 80 kb. Instead, repetitive DNA sequences have been localized there, the structures of which suggest that they may have been involved in the evolution of the V kappa gene-containing regions. The V kappa pseudogene containing W regions, that had been transposed in evolution from the short to the long arm of chromosome 2 by a pericentric inversion, may have been derived from the O regions according to structural homologies between defined sections of the O and W regions.
人类免疫球蛋白κ轻链基因座的两个大区域，即所谓的O区域，已在黏粒和λ噬菌体克隆上得到表征。这两个区域非常相似，但并非完全相同的重复序列，它们分别属于κ基因座的近端（p）和远端（d）拷贝。Op和Od区域分别由90 kb和120 kb的重叠群组成，包含20个已测序的Vκ基因和假基因。在这两个重复序列中发现三对Vκ基因几乎完全相同，而至少其中两个基因的同种异型差异相当大。重复基因之间的相似性可能与以下事实有关：κ基因座的两个拷贝以回文样方式排列，O区域的5'端彼此相对（CκJκBLpApOp - OdAdLd）。这可能有助于使序列趋于平衡。在Op和Od之外，约80 kb范围内未发现其他Vκ基因。相反，重复DNA序列定位于此，其结构表明它们可能参与了含Vκ基因区域的进化。根据O区域和W区域特定部分之间的结构同源性，在进化过程中通过着丝粒倒位从2号染色体短臂转座至长臂的含Vκ假基因的W区域，可能源自O区域。
