Boyd R T, Goldrick M M, Gottlieb P D
Proc Natl Acad Sci U S A. 1986 Dec;83(23):9134-8. doi: 10.1073/pnas.83.23.9134.
Two phenotypic markers of mouse immunoglobulin kappa light chains, the IB-peptide marker and the Ef1a isoelectric focusing marker, are expressed by the C58/J, AKR/J, RF/J, and PL/J strains (called expressor strains) but not by BALB/c and most inbred strains. Expression is linked to the kappa light-chain locus and the Lyt-2/Lyt-3 genes on chromosome 6. Light chains bearing these markers belong to a group of variable region kappa chain (V kappa) regions called V kappa Ser, which has a serine amino terminus and a framework 1 region not observed to date among BALB/c light chains. Southern hybridization of genomic DNA with a V kappa Ser-specific cDNA probe has demonstrated a single strongly hybridizing DNA fragment in all strains of mice tested. Characteristic restriction enzyme polymorphisms define the V kappa Ser alleles of expressor (Igk-VSera) and nonexpressor (Igk-VSerb) strains. In the present study, the unrearranged V kappa Ser gene and its flanking regions from an expressor (C.C58) and nonexpressor (BALB/c) strain have been cloned and their nucleotide sequences determined. The C.C58 V kappa Ser gene isolated (the Igk-VSera allele) was shown to code for the two phenotypic markers described. While the nucleotide sequence of the BALB/c coding region (the Igk-VSerb allele) shows 97% identity with the C.C58 gene, single nucleotide substitutions lead to structural changes in the encoded protein which render it IB-negative and Ef1a-negative. These differences alone can explain the failure of strains containing the BALB/c allele to express these kappa-chain phenotypic markers. Also, the BALB/c gene contains a single substitution in a conserved octamer sequence approximately equal to 100 nucleotides upstream of the coding region, which could affect its expression. Finally, the C.C58 allele contains a BAM5/R repetitive DNA element approximately equal to 1200 nucleotides upstream of the coding regions that is not present in BALB/c. This element gives rise to the EcoRI and BamHI restriction enzyme polymorphisms, which distinguish the Igk-VSera and Igk-VSerb alleles.
小鼠免疫球蛋白κ轻链的两种表型标记，即IB肽标记和Ef1a等电聚焦标记，由C58/J、AKR/J、RF/J和PL/J品系（称为表达品系）表达，但BALB/c和大多数近交系不表达。这种表达与6号染色体上的κ轻链基因座和Lyt-2/Lyt-3基因相关。带有这些标记的轻链属于一组可变区κ链（Vκ）区域，称为Vκ Ser，其具有丝氨酸氨基末端和迄今在BALB/c轻链中未观察到的框架1区域。用Vκ Ser特异性cDNA探针进行基因组DNA的Southern杂交，在所有测试的小鼠品系中都显示出一个单一的强杂交DNA片段。特征性的限制性内切酶多态性定义了表达品系（Igk-VSera）和非表达品系（Igk-VSerb）的Vκ Ser等位基因。在本研究中，已从一个表达品系（C.C58）和一个非表达品系（BALB/c）克隆了未重排的Vκ Ser基因及其侧翼区域，并测定了它们的核苷酸序列。分离出的C.C58 Vκ Ser基因（Igk-VSera等位基因）被证明编码所述的两种表型标记。虽然BALB/c编码区的核苷酸序列（Igk-VSerb等位基因）与C.C58基因有97%的同一性，但单核苷酸替换导致编码蛋白的结构变化，使其成为IB阴性和Ef1a阴性。仅这些差异就可以解释含有BALB/c等位基因的品系无法表达这些κ链表型标记的原因。此外，BALB/c基因在编码区上游约10
