STIM1 is present at the surface of hippocampal neurons.
(A) Cell surface STIM1 protein populations were examined biochemically by labeling cortical neurons (DIV >21) with NHS-LC-biotin followed by precipitation of the resulting lysates with neutravadin biotin binding beads. Precipitates were resolved by SDS-PAGE and analyzed via western blot with α-STIM1 (top) or α-GluR1 (bottom) antibodies. Representative blots depicted from 3 independent experiments. (B) Rat hippocampal neurons (DIV 21 and 4) were infected with Sindbis STIM1-GFP virion. Expression was allowed to continue for 12 hours. The cells were then live-labeled with α-GFP-Alexa 594 conjugated antibodies (red) prior to fixation, permeabilization, and immunolabeling with α-PSD-95 antibodies (blue). As depicted in (B–C), STIM1-GFP is present on the surface of dendrites and growth cones. Representative images depicted from >40 images acquired. Whole cell scale bar = 20 µm; dendrite scale bar = 10 µm; Growth cone scale bar = 5 µm.