The invention relates to a DNA sequences for regulating transcription of a structural gene encoding a polypeptide in a eukaryotic host cell comprising (a) a first DNA sequence to which RNA polymerase binds which DNA sequence comprises a mRNA initiation site; and further (b) one or more DNA sequence(s) to which RNA polymerase binds with or without a mRNA initiation site. The invention also relates to a DNA construct and an expression vector and a host cell comprising the DNA sequence of the invention.