A zein gene of maize is transcribed from two widely separated promoter regions.

The zein proteins are the major storage proteins of maize endosperm. They are made from large amounts of zein RNAs of several distinct sizes, ranging from the small 900 base final size RNA to precursor forms of over 3800 bases. The 900 base mRNA and the smallest precursor mRNA of 1800 bases are transcribed from two distinct promoter regions, P1 and P2. In vitro transcription of a maize genomic clone containing a zein gene pML 1 allowed both promoters to be mapped. The sequence of pML 1, covering the two promoter regions, contained consensus transcription start sequences at both of the predicted promoters. S1 mapping with RNA prepared from maize endosperm showed that both P1 and P2 are active in vivo as double starts.