| Abstract: | Two-dimensional gel electrophoresis was used to compare the protein composition of normal (D strain) and symbiont-containing (xD strain) A. proteus. Over 500 different peptide spots could be identified on a typical gel of cytosol proteins. In addition to differences in a few minor peptides, one prominent polypeptide with an isoelectric point of about 5.5 and a molecular weight of about 29,000 was present in the cytoplasm of symbiont-containing amoebae and in the endosymbionts but not in D-strain amoebae. When endosymbionts were removed from xD-strain amoebae, the xD-specific polypeptide also disappeared, suggesting that it is produced by the endosymbionts. |
