CHARACTERIZATION OF PROTEIN-SYNTHESIS FACTORS FROM RABBIT RETICULOCYTES

As part of our efforts to characterize eukaryotic translation factors, we have sequenced a number of them chemically and inferred sequences from cDNA clones. To our surprise, there appears to be extensive identity of amino acid sequence in most factors characterized to date in that within mammalian species, usually greater than 99% identity is observed. Extreme examples are rabbit EF-1α which is 100% identical to human EF-1α and rabbit eIF-4AI and eIF-4AII which are 100% identical to mouse eIF-4AI and eIF-4AII for those amino acids sequenced ( 398 406 and 156 407, respectively). An extended analysis has been made of EF-1α which in rabbit has three different post-translational modifications, dimethyllysine, trimethyllysine and glycerylphosphorylethanolamine. A comparison of the primary structure of EF-1α to E. coli EF-Tu indicates an overall sequence identity of 33%. However, within the amino terminal 180 amino acids (the GTP-binding domain), there are found regions of much greater identity ( 50 85 = 59%). © 1990.