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Single-Cell Biophysics: Measurement, Modulation, and Modeling
Poster Abstracts
80
71-POS
Board 36
Track STIM1 and Orai1 Molecules in Live Cells
Xianan Qin
1
, Sangkwon Lee
3
, Kaitlin Chan
2
, Min Zhang
2
, Chenglong Yu
2
, Jun Chu
4
, Chan
Young Park
3
, Hyokeun Park
1,2
.
1
The Hong Kong University of Science and Technology, Kowloon, Hong Kong SAR,
China,
2
The Hong Kong University of Science and Technology, Kowloon, Hong Kong SAR,
China,
3
Ulsan National Institute of Science and Technology, Ulsan, South Korea,
4
Shenzhen
Institutes of Advanced Technology, Chinese Academy of Science, Shenzhen, Guangdong,
China.
Ca
2+
inside cells plays important roles in biological processesy. The store operated calcium entry
(SOCE) can be regulated by STIM1 (a calcium sensor in the membrane of ER) and Orai1 (a
calcium channel in the plasma membrane). STIM1 binds to Orai1 , and activates the Orai1
channel after the calcium depletion in ER. Although there are several reports about the molecular
mechanism of Orai1 and STIM1, the detailed dynamics of STIM1 and Orai1 assembly is not
clearly understood yet. We tracked STIM1 and Orai1 particles using our real time single-particle
tracking setup. Using single-particle tracking, we calculated the diffusion coefficients of
individual STIM1 and Orai1 particles. The diffusion coefficients of STIM1 and Orai1 particles
were widely distributed when the ER calcium was at resting state. The depletion of ER calcium
store after the treatment of Thapsigargin (TG) decreased the diffusion coefficients drastically.
We further obtained the diffusion coefficient map and the potential energy landscape of STIM1
and Orai1 inside cells using Bayesian inference analysis. We also found that the potential energy
landscapes of STIM1 and Orai1drastically changed after ER calcium depletion. These studies
imply the diffusion-trapping of STIM1 and Orai1 in their assembly.