Peptide sequencing of the chick oviduct progesterone receptor form B

The progesterone receptor form B has been isolated to apparent homogeneity from large scale preparations of laying hen oviduct cytosol. The quantities obtained were sufficient to monitor the separation of tryptic peptides on HPLC columns. Using a multi-dimensional microbore HPLC peptide purification protocol, several peptides were isolated in homogeneous form and sequenced up to 34 steps at the sub-40 pmol level using a gas phase sequenator. One of the peptides showed a striking homology with sequences of the putative steroid binding domain of the human glucocorticoid receptor; this region is also conserved in the human and chick estrogen receptor.