Two naturally‐occurring isoforms and their expression of a glucocorticoid receptor gene from an androgen‐dependent mouse tumor

We have isolated cDNAs encoding the glucocorticoid receptor from an androgen-dependent mouse tumor, Shionogi Carcinoma 115. The nucleotide sequence of the receptor revealed two different forms, designated as SC-GR I and SC-GR II. Both forms have a one-base substitution in the DNA binding domain of the wild-type mouse glucocorticoid receptor. Furthermore, SC-GR II has a three-base insertion in the interfinger region of this domain. By expressing the receptor cDNAs in cultured cells with MMTV-CAT reporter plasmid, SC-GR II was found to have about half of the activity of the wild-type mouse glucocorticoid receptor induced by either physiological or pharmacological doses of dexamethasone.