Isolation and molecular characterization of bovine T-cell receptor genes

从牛外周血淋巴细胞和胸腺淋巴细胞构建的cDNA文库中测定牛T细胞受体（TCR; α、β、γ和δ链）基因的核苷酸序列.在30个牛TCR α链的阳性cDNA克隆中，20个包含完全和正确的重排，而4个仅包含一个恒定（C）区，6个由于不完全重排而无功能。牛Calpha基因由140个氨基酸残基组成，与人和小鼠的Ca区具有惊人的相似性.在38个TCR β链的cDNA克隆中，22个被重排并含有功能可变（V）基因片段。这些克隆初步分为9个TCR-V基因家族，对应于人TCR-V家族。发现两个不同的C β基因片段，两个C区均由178个氨基酸残基组成.在9个牛TCR γ链cDNA克隆中，只有4个克隆是重排的， ...更多信息 V、Joining（J）和C基因片段，但其余5个含有J和C或仅C基因片段而没有V基因片段。发现了三种Cgamma，并将其命名为Cgamma1、Cgamma2和Cgamma3。与人和小鼠的C γ相比，牛的C γ序列要长得多，有27 - 55个氨基酸对应于铰链区和连接区.在分离的3个牛TCR δ链cDNA克隆中，发现了2个TCR V基因片段和3个J基因片段，牛C δ基因片段的核苷酸序列和推导的氨基酸序列（155个氨基酸残基）在种间具有很好的保守性.在以小鼠编码α的DNA为探针从牛淋巴细胞cDNA文库中筛选牛TCR α链基因的过程中，我们分离到了11个编码乳酸脱氢酶（LDH）-A同工酶的cDNA克隆。这些cDNA克隆编码332个氨基酸残基，其蛋白经凝胶电泳鉴定为LDH-A同工酶.通过将来自三种类型（小牛、皮肤和胸腺）的牛淋巴肉瘤移植到BALB/C nu/nu小鼠，建立了散发性牛白血病肿瘤细胞系，并检测了TCR α、β、γ和δ基因的表达。在肿瘤细胞中检测到成熟或截短的TCR-β、-γ和-δ转录物，但在cDNA克隆分析中发现它们都是无功能的。在从胸腺型淋巴肉瘤的TCR-γ基因的异常转录本构建的cDNA文库中，分离出TCR γ链的新C区（Cgamma4）。少

The nucleotide sequences of bovine T-cell receptor (TCR ; alpha, beta, gamma, and delta chains) genes which from cDNA libraries constructed from bovine peripheral blood lymphocytes and thymic lymphocytes were determined.1. Of 30 positive cDNA clones for bovine TCR alpha chain, 20 contained complete and correct rearrangements, whereas 4 contained only one Constant (C) region, and 6 were nonfunctional because of incomplete rearrangement. The bovine Calpha gene is composed of 140 amino acid residues with striking similarity to the Ca region of human and mouse.2. Of 38 CDNA clones for TCR beta chain, 22 were rearranged and contained the functional variable (V) gene segments. These clones were tentatively divided into nine TCR-V gene families which correspond to the human TCR-V family. Two different Cbeta gene segments were found, and both C regions were composed of 178 amino acid residues.3. Of 9 cDNA clones for bovine TCR gamma chain isolated, only 4 were-rearranged and contained specific … More V, Joining (J), and C gene segments, but the remaining 5 contained J and C or only C gene segments without the V gene segment. Three kinds of Cgamma were found and designated as Cgamma1, Cgamma2 and Cgamma3. Compared with human and mouse Cgamma, bovine Cgamma sequences are much longer, with 27-55 amino acids corresponding to the hinge and connector regions.4. Of three TCR delta chain CDNA clones isolated, two TCR V and three J gene segments were found. The nucleotide and deduced amino acid sequences (155 amino residues) of bovine C delta gene segment are well conserved among species.5. During the screening for bovine TCR alpha chain gene in a bovine lymphocyte CDNA library using mouse Calpha-encoding DNA as a probe, we isolated 11 CDNA clones encoding lactate dehydrogenase (LDH) -A isozyme. These LDH-A cDNA clones coded for 332 amino acid residues which protein was identified by cellogel electrophoresis as LDH-A isozyme.6. Sporadic bovine leukosis tumor cell lines were established by transplantation to BALB/C nu/nu mice from three types(calf, skin and thymic)of bovine lymphosarcoma, and examined for the expression of TCR alpha, beta, gamma and delta genes. Mature or truncated TCR-beta, -gamma and -delta transcripts were detected in the tumor cells, but all of them were found to be nonfunctional in cDNA cloning analysis. In the cDNA library constructed from the aberrant transcripts of the TCR-gamma gene of the thymic type of lymphosarcoma, a novel C region of the TCR gamma chain (Cgamma4) was isolated. Less