Biological, Environmental, & Climate Sciences (BECS) Department Seminar
"Structural Mechanism of a Conserved Calcium Leak in Protection of Life"
Presented by Qun Liu, New York Consortium on Membrane Protein Structure, New York Structural Biology Center, New York, NY
Friday, May 1, 2015, 11:00 am — John Dunn Seminar Room, Bldg. 463
Ca2+ is a ubiquitous intracellular messenger that regulates cellular activities in plants, animals and humans. Cytosolic Ca2+ is kept at a low level, but subcellular organelles such as the endoplasmic reticulum (ER) maintain Ca2+ stores. Under resting conditions, Ca2+ homeostasis is dynamically regulated to equilibrate between active calcium uptake and passive calcium leak. Ca2+ homeostasis is cytoprotective. An overloaded ER Ca2+ content promotes cell death. We determined crystal structures of a Ca2+ leak channel and characterized its biochemical functions. The structure has a novel seven-transmembrane-helix fold consisting of a centralized C-terminal helix wrapped by two triple-helix sandwiches. Lateral displacement of transmembrane helix TM2 by change of pH leaves a transmembrane pore, allowing a leak of Ca2+ across membranes. The leak is regulated by a di-aspartyl pH sensor consisting of two conserved aspartate residues. The leak is intrinsic to all kinds of cells and is cytoprotective for life.
Hosted by: Huilin Li
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