Molecular cloning and nucleotide sequencing of human immunoglobulin € chain cDNA

DNA complementary to mRNA of human immunoglobulin E heavy chain (€ chain) isolated and purified from U266 cells has been synthesized and inserted into the PstI site of pBR322 by G-C tailing. This recombinant plasm id was used to transform E.coliXl776 to screen 1445 tetracycline resistant colonies. Nine clones (pGETl - 9) containing cDNA coding for the human e chain were recognized by colony hybridization and Southern blotting analysis with a nick-translated human IgE genome fragment. The nucleotide sequence of the longest eDNA contained in pGET2 was determined. The results indicate that the sequence of 1657 nucleotides codes for 494 amino acids covering a part of the variable region and all of the constant region of the human e chain. Most of the amino acid sequence deduced from the nucleotide sequence is in substantial agreement with that reported. Furthermore a termination codon after the -C00H terminal amino acid marks the beginning of a 3' untranslated region of 125 nucleotides with a poly A tail. Taking this into account, the structure of the human e chain mRNA, except a part of the 5' end, is conserved fairly well in the cDNA insert in pGET2.