Molecular endpoints of Ca2+/calmodulin- and voltage-dependent inactivation of Ca(v)1.3 channels.

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Ca(2+)/calmodulin- and voltage-dependent inactivation (CDI and VDI) comprise vital prototypes of Ca(2+) channel modulation, rich with biological consequences. Although the events initiating CDI and VDI are known, their downstream mechanisms have eluded consensus. Competing proposals include hinged-lid occlusion of channels, selectivity filter collapse, and allosteric inhibition of the activation gate. Here, novel theory predicts that perturbations of channel activation should alter inactivation in distinctive ways, depending on which hypothesis holds true. Thus, we systematically mutate the activation gate, formed by all S6 segments within Ca(V)1.3. These channels feature robust baseline CDI, and the resulting mutant library exhibits significant diversity of activation, CDI, and VDI. For CDI, a clear and previously unreported pattern emerges: activation-enhancing mutations proportionately weaken inactivation. This outcome substantiates an allosteric CDI mechanism. For VDI, the data implicate a "hinged lid-shield" mechanism, similar to a hinged-lid process, with a previously unrecognized feature. Namely, we detect a "shield" in Ca(V)1.3 channels that is specialized to repel lid closure. These findings reveal long-sought downstream mechanisms of inactivation and may furnish a framework for the understanding of Ca(2+) channelopathies involving S6 mutations.





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Tadross, Michael R, Manu Ben Johny and David T Yue (2010). Molecular endpoints of Ca2+/calmodulin- and voltage-dependent inactivation of Ca(v)1.3 channels. J Gen Physiol, 135(3). pp. 197–215. 10.1085/jgp.200910308 Retrieved from

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Michael Raphael Tadross

Assistant Professor of Biomedical Engineering

Dr. Tadross' lab develops technologies to rapidly deliver drugs to genetically defined subsets of cells in the brain. By using these reagents in mouse models of neuropsychiatric disease, his group is mapping how specific receptors on defined cells and synapses in the brain give rise to diverse neural computations and behaviors.  The approach leverages drugs currently in use to treat human neuropsychiatric disease, facilitating clinically relevant interpretation of the mapping effort.

He received his B.S. degree in Electrical & Computer Engineering at Rutgers University, an M.D.-Ph.D. degree in Biomedical Engineering at the Johns Hopkins School of Medicine, and completed his postdoctoral study in Cellular Neuroscience at Stanford University. He began his independent research program as a fellow at the HHMI Janelia Research Campus.

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