Sequence analysis of a cDNA clone of a gene encoding a component of a putative phosphorylcholine-specific T...

We have isolated a putative phosphorylcholine (PC)-T cell suppressor factor (TsF) cDNA clone, p6-5, from a cDNA library of a T hybridoma which constitutively secretes a PC-TsF in vitro [8]. In the present study, we determined the nucleotide sequence of the p6-5 gene and found that the p6-5 sequence is 86% homologous to rat preproelastase 1 gene, one of the serine protease genes. An oligopeptide (14 mer, TsF14) deduced from the p6-5 sequence was synthesized and antisera against TsF14 were prepared in rabbits. Anti-TsF14-conjugated Sepharose 4B specifically absorbed the PC-TsF activity from the culture supernatant of PC-TsF-secreting T hybridomas. In contrast, the binding molecule eluted from the anti-TsF14-conjugated Sepharose suppressed the antibody response PC specifically. These results indicated that the p6-5 polypeptide is a component of the PC-TsF molecule.