CHARACTERIZATION OF YEAST EF-1-ALPHA - NONCONSERVATION OF POSTTRANSLATIONAL MODIFICATIONS

Elongation factor 1alpha (EF-1alpha) is an abundant cellular protein a nd its amino-acid sequence has been inferred from numerous organisms, including bacteria, archaebacteria, plants and animals. In large measu re, it would appear that the overall structure has probably been maint ained given the 33% identity and 56% similarity of Escherichia coli EF -Tu with human EF-1alpha. Chemical sequencing of EF-Tu and EF-1alpha h as revealed that these proteins are post-translationally modified. In order to assess the possible function of these modifications, we have chemically sequenced the EF-1alpha from the lower eukaryote Saccharomy ces cerevisiae (yeast). To our surprise, the methylation pattern of ye ast EF-1alpha was quite different from either rabbit or brine shrimp E F-1alpha with only the trimethyllysine at position 79 conserved althou gh the yeast protein is 81% identical to rabbit EF-1alpha. A dimethyll ysine was observed at position 316 which corresponds to a trimethyllys ine in brine shrimp and rabbit EF-1alpha. The other positions in yeast EF-1alpha which were methylated were unrelated to the other six possi ble positions for modification observed in brine shrimp or rabbit EF-1 alpha. In addition, the unique glycerylphosphorylethanolamine observed in mammalian EF-1alpha and suspected in brine shrimp EF-la was not fo und in yeast EF-1alpha.