IDENTIFICATION OF GENES FOR THE CONSTANT REGION OF RABBIT T-CELL RECEPTOR BETA-CHAINS

c[complementary]DNA clones are described from thymus mRNA of a young rabbit that have sequences highly homologous to the human and murine T-cell receptor .beta.-chain constant region (C.beta.). In rabbit, man and mouse there is a conserved extra Cys in the constant region that could lead to a free thiol group or alternative disulfide bond formation depending on the locations and total numbers of Cys in assembled receptor molecules. A cDNA clone (CL ANA 11) with 571 bases 5'' of the C.beta. coding sequence has an open reading frame starting at a Met codon that encodes 141 amino acids in frame with the C.beta. sequence. The encoded sequence has no resemblance to known Ig or .beta.-chain variable regions or other known proteins. An oligonucleotide probe from the 5'' end of the encoded protein hybridizes to an .apprxeq. 2-kilobase genomic DNA fragment that contains C.beta. gene sequences and to an .apprxeq. 8-kilobase mRNA species in the thymus mRNA preparation from which the clone was derived. Within the 5'' coding sequence there is a stretch of 211 bases containing strings of alternating purines and pyrimidines that may form Z-DNA. The sequence of the last 55 base pairs adjacent to C.beta. resembles the corresponding segment of mouse cDNA clone 86T3 that contains sequence 5'' of the mouse C.beta.1 gene. Although the function of a potential protein encoded by the 5'' end of CL ANA 11 is unknown, it could play a role in regulation of thymocyte growth and differentiation.