Ref ID : 4877
I. Finger, D. Audi, M. Bernstein, S. Voremberg, K. Harkins, M. Birnbaum, A. Lynn, and M. Lawlor; Switching of Paramecium Surface Antigen Types with Purified Antigen and Conditioned Medium Containing 70 kD Proteins. Arch.Protistenk 146:373-381, 1995/96
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Paramecia can be induced to change the kind of i protein characteristic of their surfaces by either cell contact with paramecia of a different serotype or after exposure to cell-free conditioned media in which growth has occurred. We have examined these media by SDS-polyacrylamide gel electrophoresis and have detected surprisingly few proteins. One protein which is present only in media which can switch serotypes has an apparent molecular weight of about 70 kD. The amount of this protein as judged by Coomassie blue staining is correlated with the effectiveness of a medium in eliciting antigenic switching. The 70 kD proteins are found not only in media which transform but also in "purified" surface antigen preparations, as shown by immunoblots using antisera prepared against 70 kD proteins isolated from antigen by gel filtration. Antibodies to these proteins generally are detectable by enzyme-linked immunosorbent assay in all antisera made against surface antigen.