Biological structure of ER-a36. (A) The exon of ER-α36 from intron1 of ER-α66 gene is designated as 1′. The extra exon of ER-α36 gene that is beyond 8 exons of ER-α66 gene is numbered as 9. ER-α36 has a unique 27 amino acid domain at C-terminus. Deletions are indicated by a single line. (B) Protein structure of ER isoforms includes A/B domain contains transcriptional-activation function AF-1, C domain represents DNA-binding-domain (DBD), D domain contains nuclear localization signal (NLS), and E domain corresponds to ligand binding domain (LBD) and transcriptional-activation function AF-2. ER-α36 lacks AF-1 and AF-2. The last 27 amino acids of ER-α36 are indicated by a shaded box.