Fig. 1. Synapsin I is present in non-neuronal cells. (A,B) Immunoblot analysis of total homogenates of rat brain (1 µg), rat liver (200 µg), rat hepatocytes (Hep, 200 µg) and NRK cells (200 µg) using antibody SNH1 (A) and SNT1 (B). Both antibodies detected an 85 kDa band (*) in non-neuronal samples that co-migrated with rat brain synapsin I. Molecular mass standards (in kDa) are indicated at the left of each panel. (C) Antibodies to synapsin I immunoprecipitate an 85 kDa protein from liver. Proteins from brain (0.5 mg total protein) or liver (10 mg total protein) cytosols were immunoprecipitated with SNH1 (top panel) or SNT1 (bottom panel) and analyzed by immunoblot with Ab#213. Both antibodies immunoprecipitated an 85 kDa protein from either brain (Brain +ab) or liver cytosol (Liver +ab) that was recognized by Ab#213; the protein was not immunoprecipitated from liver cytosol incubated with Protein A-Sepharose beads alone (Liver -ab). (D) The 85 kDa protein is absent from livers of synapsin I- and II-deficient mice. Total homogenates of brain or liver from wild-type mice (wt) or synapsin I and II-deficient mice (syn-/-) were analyzed by immunoblot using Ab#212 (SynI) or antibodies to tubulin (Tub) as a loading control. An 85 kDa protein was detected in both brain and liver of wild-type mice that was absent from brain and liver of synapsin I and II-deficient mice.
