Immunological identification of a new 14×103Mr membrane-bound protein in Torpedo electric organ

A series of monoclonal antibodies binding to different epitopes shared by a 14×103Mr membrane-bound polypeptide has been obtained. By indirect immunofluorescence, it was shown that the 14×103Mr antigen is present in various cell types in Torpedo electric organ and muscle, especially fibroblasts, capillary endothelial cells, axonal cuff cells and, to a lesser extent, Schwann cells. At the electron-microscope level, after immunogold labelling, the antigen was found associated with the external surface of the plasma membrane of these cells, with the exception of the axonal cuff cells where part of the labelling was intracellular. The possible biological role of this 14×103Mr protein is unknown but preliminary experiments suggest that this antigen has affinity for other Torpedo electric organ membrane proteins.