Detection of 180 kDa proteins in electroplax sodium channel preparations

1. Co-isolating proteins (M(r) 170,000-220,000) from sodium channel preparations made from the electric organ of the electric eel (Electrophorus electricus) were detected on Western blots using monoclonal antibodies. 2. Similar protein patterns were seen on immunoblots containing immunoprecipitated protein from eel muscle and brain tissues but not heart. 3. These co-isolating proteins could be separated from the mature TTX-sensitive channel protein (M(r) 280,000) using a lentil lectin-Sepharose column. 4. The 180 kDa proteins do not appear to be channel-related and can be detected as contaminants in electroplax sodium channel preparations using the monoclonal antibodies described here.