Substrate-induced conformational changes in sarcoplasmic reticulum Ca2+-ATPase probed by surface modification using diethylpyrocarbonate with mass spectrometry

► Use of DEPC modification and mass spectrometry to identify 15 residues from SERCA. ► The effects of Ca2+, ATP, and MgF4 at these residues have been addressed. ► The reactivity of many residues was consistent with the crystal surface structures. ► Similar structural changes occur both in the membranous and crystalline states. ► 4 Residues near the interface of 3 cytoplasmic domains suggest larger changes.