Fig. 1.

Expression of Syt IV in cultured astrocytes. (a) Western blots demonstrate the presence of Syts IV, V, and XI (black arrowheads) in cultured astrocytes (recombinant protein is shown in the left lane). Anti-Syt XI reacts with three bands, one of the appropriate molecular mass and two that are smaller (gray arrowheads). (b) RT-PCR on brain (Upper) and cultured astrocytes (Lower) shows that Syts IV and V, but not Syts I or II, transcripts were amplified from astrocyte cultures. (c) Double label of GFAP (red) and Syt IV (green) on pure astrocyte culture. (Bar, 10 μm.) (d) Double label of Syts I (red) and IV (green) on astrocyte-neuron coculture shows that Syt IV is expressed predominantly in astrocytes (white arrows), although some reactivity in neuronal somata is seen in cultures (arrowheads). (Bar, 20 μm.)