Exon sequences are conserved, but intron sequences vary
Through the use of recombination DNA technology, it could be shown that the exon sequences of more than one genes (for same related functions) in the same species or in different species, often have similar DNA sequences. However, the corresponding intron sequences differ substantially. This was demonstrated for two β globin genes of mouse. This property has been utilized in selecting exon sequences of heterologous genes for isolation of related genes in different species.