Multiple glucocorticoid receptor transcripts in membrane glucocorticoid receptor-enriched S-49 mouse lymphoma cells

A cDNA library from plasma membrane glucocorticoid receptor-enriched (mGR( +)) S- 49 mouse T lymphoma cells was screened with full-length rat intrace llular CR (iGR) cDNA, BUGR-2 antibody, and PCR amplimers to portions of the mouse CR cDNA. One or two single-base substitutions resulting in amino aci d changes (which do not incapacitate the receptor) were found in all but on e clone: Val437 --> Gly (located in the first zinc finger), and Glu546 --> Gly (in the steroid-binding domain). Two previously unidentified exon 1 var iants (1D and 1E), and two of three previously reported variants (1A, 1B) w ere found to be spliced onto the common exon 2. Exon 1D- and 1E-containing transcripts were confirmed by direct sequencing of amplimers from reverse t ranscriptase-coupled PCR. RNase protection studies revealed that one of the se transcripts was expressed in mGR(+ +) cells only, but not in two mGR-les s (mGR(- -) S-49, and AtT-20 mouse pituitary) cell lines. These studies sug gest that at least four promoters may be responsible for the control of CR (iGR and mGR) types in mouse lymphoma cells. (C) 1999 Wiley-Lisa Inc.