We cloned and sequenced T cell receptor (TCR) α and β chain cDNA from a λgt10 library obtained from a murine I-Ak autoreactive helper T cell clone MS202. Two types of cDNA clones for the α chain and one for the β chain were obtained. The two α chain transcripts used two different Vα genes: Vα 4, joined to Jα 11.2; and Vα 5, joined to JαTA13. The four Vα4 cDNA clones obtained did not have a complete sequence, lacking the leader portion. The Vα4 genomic gene segment of MS202 was revealed to contain two exons corresponding to the Vα4.MD13 cDNA sequence, and the potential RNA splicing signals between the two exons were Intact. Both of the a chain cDNA clones showed In-frame rearrangements. Immunoprecipitation of 125I-surfacelabeled lysate of MS202 with anti-TCR antiserum and subsequent electrophonetic analyses indicated that only one of the α chain polypeptides was expressed on the cell surface. Thus, allelic exclusion of the α chain in MS202 is achieved by post-transcriptional regulation rather than rearrangements.
All Science Journal Classification (ASJC) codes
- Immunology and Allergy