Isolation and molecular characterization of bovine T-cell receptor genes

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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