Report on participation in Biophysical Society 49th
Schedule of the trip
2/11 Osaka (Japan) ¨@Los Angels (USA)
2/12-16 Biophyscial Society 49th annual meeting, Long Beach (USA)
2/17-18 Los Angels (USA) ¨@Osaka (Japan)
Biophysical society 49th annual meeting was held during February 12-16
in Long Beach, California. There were many symposiums and posters in
this meeting because many researchers related to biophysics participated
in this meeting, and they have diverse interests. I attended symposiums
and posters related to single molecule biophysics and imaging techniques.
I made poster presentation entitled gsingle-molecule imaging of trimeric
G protein in Dictyostelium cellsh on day 3. In this study, we observed
single molecules of yellow fluorescent protein (YFP) fused alpha subunit
of the heterotrimeric G protein (G alpha) in living Dictyostelium cells
by total internal reflection fluorescence microscopy (TIRFM). We found
that individual G alpha-YFP molecules came up to and off from the membranes,
showing translocation of G proteins from cytoplasm to plasma membrane.
We showed that the binding durations of Ga-YFP on the membrane were shorter
than the bleaching time of the fluorescent protein. This result suggests
G protein dissociate from membrane. We also showed the slower decay of
total fluorescent intensity on plasma membrane of cell, which expressed
G alpha-YFP. This result indicates fluorescent recovery by translocation
of G alpha-YFP from cytoplasm. The binding duration of G alpha-YFP became
shorter by cAMP stimulation, suggesting receptor-mediated acceleration
of the dissociation of G proteins from membrane. Translocation of Ga
is not commonly accepted although there are some reports about such phenomenon.
In general, it is thought G protein located stably in plasma membrane.
Therefore some people are skeptical about our date and I was questioned
some points about our experiment. Anyway I had a meaningful discussion
Perspective and future plans
In general, it is thought that GPCR and their coupled G protein operate
on 2-dimensional plasma membrane. In contrast our data showed that
G proteins operate 3-dimensionally. These results provide new insight
in signal transduction of cell. However, our data allows of some dispute
now. We have to show other supporting data. Additionally we must investigate
the relationship between translocation of G proteins and sensibility
Finally, I would like to express to COE program my deepest gratitude
for financial support of the trip.