Proteins of the plasma membrane skeleton in entodiniomorphid ciliates: An immunological study using monoclonal...

We have previously reported biochemical evidence suggesting that a 58 Kd protein (p 58) is a major constituent of the membrane skeleton of the ciliated protozoan Entodinium bursa. In this study, monoclonal antibodies were produced in order to determine the distribution of p 58 in the four entodiniomorphids Entodinium bursa, Eudiplodinium maggii, Epidinium caudatum and Polyplastron multivesiculatum. Two clones, 78-116-4 and 76-12-7, were selected from a set of hybridomas obtained using either p 58 or whole proteins from cytoskeletal preparations of Eudiplodinium maggii as immunogens. Specificity tests by Western blot analysis indicate that MABs 78-116-4 and 76-12-7 both recognize p 58 in Entodinium bursa and protein ranging from 59 to 62 Kd in the three other species examined. Immunocytochemical evidence is presented which confirms that 78-116-4 and 76-12-7 antigens are located in the membrane skeleton. This suggests that the latter may represent homologous proteins implicated in the maintenance of a consistent pattern of cortical organization in the entodiniomorphid ciliates.