Biophysical studies of the interaction between calmodulin and the R287-T311 region of human estrogen receptor α reveals an atypical binding process

► We characterized the interaction between ERα-derived peptides and calmodulin. ► The ERα 287-294 region belongs to the calmodulin-binding site. ► The ERα peptide 287-311 binds calmodulin with an atypical 2:1 stoichiometry. ► This atypical binding involves concerted structural changes of calmodulin domains.