Cloning and nucleotide sequence of the murine interleukin‐3 gene

Abstract

Southern hybridization analysis using a probe derived from a murine interleukin‐3 (IL‐3) cDNA clone revealed the presence of a single IL‐3 gene in the haploid murine genome. An 8600‐base‐pair (8.6‐kb) murine genomic EcoRI fragment containing the IL‐3 gene was isolated by screening a library of size‐fractionated genomic EcoRI fragments cloned in λgt WES. λB. The nucleotide sequence of a 3.5‐kb region of the cloned DNA encompassing the IL‐3 gene was determined. The gene contains four introns of 96, 993, 135 and 122 base pairs (bp), located within the coding region. The large intron contains 12 copies of a 14–15‐bp tandem repeating sequence which resemles a human cellular homologue of a BKV enhancer sequence. The nucleotide sequence of the exons agrees exactly with that of an IL‐3 cDNA cloned from WEHI‐3, a tumorigenic cell line which over‐produces IL‐3, establishing that the unprocessed primary structure of IL‐3 is identical in WEHI‐3 and in BALB/c mice. Southern hybridization has revealed genomic alteration in the vicinity of the IL‐3 gene in WEHI‐3 cells.