Figure 4.

Snapin is membrane associated and cytosolic. (A) Snapin is evenly partitioned between membrane-associated (P2) and soluble fractions (S2). H, unfractionated homogenate. Twenty micrograms of each fraction was loaded. A representative of two different fractionations and Western blots is shown. (B–E) Hippocampal neurons cultured for 4, 7, and 12 d.i.v. were double labeled for snapin and EEA1, an early endosomal marker (B); TGN-38, a trans-Golgi marker (C); phalloidin, a plasma membrane marker (D); or synaptophysin, a synaptic marker (E). The majority of snapin does not colocalize with any of the markers and is absent from the nucleus (E). A fraction of snapin colocalizes with the plasma membrane (D). Bar, 20 μm. The confocal z-sections shown are optimized for organelle localization.