Conformational Dynamics of Human SERCA1a in ATP-Induced Calcium Transport

The sarcoplasmic/endoplasmic reticulum calcium ATPase (SERCA1a) is essential for muscle function, mediating calcium transport across the sarcoplasmic reticulum membrane. Understanding the conformational states of SERCA1a during ATP binding and hydrolysis is vital for elucidating its transport mechanism. This study aims to characterize the structural dynamics of human SERCA1a using cryo-electron microscopy combined with molecular dynamics simulations. We determined the structures of SERCA1a in the presence of ATP and calcium ions at resolutions up to 3.4 Å. Our findings reveal distinct conformational states during the E1 and E2 transitions, indicating a previously uncharacterized intermediate form. Quantitative analysis of the ATPase activity showed a 25% increase in calcium transport efficiency under physiological conditions (p < 0.01). These insights provide a deeper understanding of the allosteric mechanisms governing calcium transport and suggest potential therapeutic targets for conditions involving impaired calcium homeostasis. The integration of cryo-EM with computational simulations offers a powerful approach for studying complex membrane proteins at atomic resolution, highlighting the interplay between structure and function. Our study not only expands the current structural knowledge of SERCA1a but also sets a framework for future investigations into related ion transporters.