Initial screen of GPER’s submembrane domains for CaM binding.

Incremental purified CaM was titrated as the entire emission spectra of BSGPER_83–93 (SMD1, A) BSGPER_150–175 (SMD2, B), BSGPER_242–259 (SMD3, C) and BSGPER_330–375 (SMD4, D) were monitored. Initial reaction mix contained 500 nM BSGPER_x, 0.1 mg/mL BSA, and 3 mM Ca²⁺. Clear responses were observed for all SMDs.