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Crystallographic investigation and characterization of the interaction between presynaptic voltage-gated calcium channels and snare proteins Liu, Xiaohu

Abstract

Voltage-gated calcium channels (Cay) have functions ranging from regulating release of hormones and neurotransmitters, generating cardiac action potentials, and excitation-contraction coupling. At nerve terminals, N- and P/Q- type Cavs convert the action potential into aC²⁺ signal that in turn triggers neurotransmitter release. Neurotransmitter release requires several components, such as SNARE proteins. SNAREs, as well as many other presynaptic proteins, can interact with Cavs and inhibit them by increasing their inactivation. The interaction is localized in the intracellular loop between domains II and III of the CL 1 subunit, in a domain termed ‘synprint’ (synaptic protein interaction site). In this study, we tried to solve the structure of the synprint site by crystallography. To date, long needle-shape crystals were obtained; however, the quality of these crystals was not good enough for X-ray diffraction. in addition, isothermal titration calorimetry (ITC) was used to determine the interaction between SNARE protein syntaxinlA and the synprint site. It turned out that not any binding was detected, suggesting that the interaction between SNARE proteins and the presynaptic Cas, if at all present, is weak.

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Attribution-NonCommercial-NoDerivatives 4.0 International