Exploring the kinetics of the interactions controlling the gating of the Ca2+-release activated Ca2+ channel

• Main Author: Zhang, Ai
• Other Authors: Said Eshaghi
• Format: Final Year Project
• Language: English
• Published: 2011
• Subjects: DRNTU::Science::Biological sciences
• Online Access: http://hdl.handle.net/10356/44746
• Institution: Nanyang Technological University

Calcium- release activated calcium channels (ORAI) are essential for sustained cytosol [Ca2+] elevation which is required for T cell activation and adaptive immunity. Upon ER luminal Ca2+ depletion, ER Ca2+ sensor STIM1 aggregates and translocates to the ER-PM junction, where it binds and activates ORAI1 channel. But the fundamental issue regarding the kinetics of STIM1-ORAI1 interaction is unresolved. Here we use surface plasmon resonance technique to study STIM1-ORAI1 binding kinetics, and size exclusion chromatography coupled with light scattering technique to study STIM1 aggregation via in vitro assays. Our results suggest a possible gating mechanism of ORAI1 channel: coiled-coil 1 domain of STIM1 holds it to ORAI1 channel while its coiled-coil 2 and coiled-coil 3 domains interact with and thus opening ORAI1 channel in an on and off fashion.