Fig. 3.

Lack of Shaker clustering inSh¹⁰² mutants. A, Anti-Shaker immunoreactivity in a third instar Sh¹⁰² larva, showing the absence of immunoreactivity at synaptic regions.B, Anti-DLG immunoreactivity in a differentSh¹⁰² preparation, showing normal DLG distribution at type I synapses. Scale bar, A, B, 20 μm. C, Western blot analysis of CS andSh¹⁰² cytosol (c) and membrane (m) fractions. Molecular weights (kDa) are indicated to the right of the blot. Multiple bands in the immunoblots are attributable to different Shaker isoforms produced by alternative splicing, which are detected by the antiserum (Rogero and Tejedor, 1995). Note the absence of proteolysis products and the very low levels of Sh¹⁰² protein in the cytosolic fraction, suggesting normal insertion of the truncated Sh protein in the plasma membrane.