Characterization of estrogen receptor cDNAs from human uterus: identification of a novel PvuII polymorphism

Using reverse transcription and the polymerase chain reaction, we have cloned estrogen receptor complementary DNAs from normal human uterine tissue. Restriction endonuclease analysis identified a polymorphic PvuII recognition site within half of the receptor cDNAs. Sequence analysis revealed a number of differences with the sequence previously reported for the ER cDNA isolated from MCF7 cells and confirmed that the codon for amino acid 400 was erroneously assigned as valine (GTG) rather than glycine (GGG). Sequencing also defined the nature of the PvuII polymorphism, with allele A coding for Glu22 and allele B (with an additional PvuII site) coding for Gln22. We demonstrate that both alleles of this receptor activate transcription of an estrogen-responsive gene to the same extent. This selective cloning method should have wide application in the investigation of naturally occurring cDNA variants from diseased tissues, such as breast cancer cell lines and primary tumor specimens.