Evidence for intermediate filaments in squirrelfish erythrophores of Holocentrus ascensionus (Rufus).

We have documented the presence of intermediate filaments (IF) in cultured erythrophores of the squirrelfish Holocentrus ascensionus (Rufus). SDS-PAGE and Western blots with monoclonal antibodies T11 and R12 demonstrated that isolated IF consisted of a pair of polypeptides of 54 and 52 kDa. Immunofluorescent studies revealed that the two proteins formed prominent radially oriented IF networks in erythrophores. Immunoelectron microscopic studies showed that the IF were distributed in a "spider-web"-like network of filaments which occasionally intersected with the microtubule surfaces. The IF proteins also were found in fish iridiphores but not in fish epithelial cells which cocultured with the chromatophores.