Intron-exon structure of the human transforming growth factor-β precursor gene

Two genomic DNA libraries, one oerived from a normal fetal liver (1) and one from the Calu-1 tumor cell line (2), were screened by hybridization to human transforming growth factor-beta (TGF-a) cDNA (3) restriction fragments. Restriction fragment mapping of the hybridizing genomic DNA fragments and DNA sequence analysis (4,5) revealed that the coding sequence of the TGF-8 precursor gene is divided in seven oistinct exons with six introns as shown below. differences organization between the gene fragments from both libraries.