Identification and sequence analysis of the 5' domain of the X and Y pseudo-ovalbumin genes

The expression of the X and Y pseudo-ovalbumin genes is stimulated by estrogen to a much lesser extent than the expression of the authentic ovalbumin gene in the chicken oviduct. Since it is possible that the primary structures of the 5' flanking regions of these genes are responsible for their differential hormonal responses, we have identified the 5' transcription domains of the X and Y pseudo-ovalbumin genes and determined their nucleotide sequences. Similar to many other eukaryotic genes, the X, Y, and ovalbumin genes each contain an (A + T)-rich heptamer located about 30 nucleotides upstream from the cap site. This sequence is TATATAT for the X and ovalbumin genes, but GATATAT for the Y gene. The 5' flanking sequences of all three genes are about 70% homologous when allowances are made for deletions and insertions. There is no obvious feature of the 5' flanking sequences of the pseudo-ovalbumin genes which can be related to differential hormonal responsiveness. Nevertheless, these 5' flanking regions appear to have been conserved relative to the intervening sequences of the pseudogenes, and thus may be important to gene function.