Esr1^tm1Arnal

441 bp of exon 1 (corresponding to amino acids 2-148) were deleted by homologous recombination. This mutation removed the coding sequence for the entire A domain and for three motifs in the B domain that are associated with the AF-1 transactivation function of the protein product. The deletion left intact the translational initiation codon (ATG) in exon 1 and 20 bp at the 3' extremity of exon 1. Immunoblot analysis of homozygote uterus extracts detected a truncated 49-kD protein product but no full length 66-kD protein product. This mutant protein was predicted to have similar functions as an endogenous 46-kD isoform that is produced in some tissues. (J:144952)