The chicken transferrin gene. Restriction endonuclease analysis of gene sequences in liver and oviduct DNA.

The organization of the chicken transferrin gene and its surrounding sequences was determined by a comparison of the restriction map of the cloned structural gene (double-stranded cDNA) with the map of the transferrin gene in genomic DNA. This analysis reveals a complex arrangement of the transferrin gene in which structural sequences are interrupted by a minimum of 6 intervening sequences, and span at least 10 kilobases in genomic DNA. Furthermore, comparison of the DNA from individual chickens of the same breed indicates considerable allelic diversity in the restriction sites for Eco RI, HindIII, and Bam HI. Quantitation of the number of transferrin genes by saturation hybridization confirms that both liver and oviduct DNAs contain only 1 transferrin gene/haploid complement, and, in addition, comparison of the restriction patterns obtained with DNA from these two tissues, as well as erythrocyte DNA, does not reveal any difference in the structural organization of the gene. We conclude that the distinct tissue-specific transcriptional regulation of this gene by steroids and iron levels in the oviduct and liver cannot be explained either by a multiplicity of genes or by somatic reorganization of the gene.