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Supplemental Information
Membrane-proximal tryptophans of synaptobrevinII stabilize priming of secretory
vesicles
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Maria Borisovska , Yvonne N. Schwarz , Madhurima Dhara , Antonio Yarzagaray , Sandra
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Hugo , Daniele Narzi , Shirley W.I. Siu , Jaideep Kesavan , Ralf Mohrmann , Rainer A.
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Böckmann and **Dieter Bruns
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Institute for Physiology
School of Medicine
University of Saarland, Germany
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Computational Biology
Department of Biology
University of Erlangen-Nürnberg, Germany
Supplementary Figure 1
Figure S1. Substitution or deletion of the membrane-proximal Trp-residues of sybII leaves the
spike phase of transmitter discharge and the pre-spike signal (‘foot’) unchanged. Properties of
amperometric spikes preceded by a ‘foot’ signal probably arise from events close to the
detector as indicated by their fast kinetics. Data were collected from sybII (n=24), -WW
(n=18), WW/AA (n=15) and WW/SS (n=15) expressing dko cells. Note that neither spike
properties nor pre-spike-properties are affected by mutating the TRP-residues. The start of the
‘foot’ signal is defined as the time point where the current amplitude exceeds two times the
standard deviation of the average baseline noise and it ends at the inflection point (determined
from maximum of the current second derivative) between the slowly increasing ‘foot’ signal and
the rapidly increasing spike current. For ‘foot’ flicker analysis, the current derivative was again
filtered at 1.2 kHz and fluctuations exceeding the threshold of ± 6 pA/ms (~4 times SD of
baseline noise) were counted. The number of suprathreshold fluctuations divided by the
corresponding ‘foot’ duration defines the fluctuation frequency. Values for spike, pre-spike
amplitude and percentage of pre-spike events are given as mean (± s.e.m.). Other values are
given as average median determined from the parameter’s frequency distribution for each cell.