title: Nucleotide binding to elongation factor 2 inactivated by diphtheria toxin.
abstract: Binding of guanosine nucleotides to purified native and ADP-ribosylated wheat germ EF-2 was measured. Both forms of EF-2 bound [3H]GDP to the same extent. [3H]GDP binding to native but not to ADP-ribosylated EF-2 was reduced in the presence of GTP and ribosomes. Binding of [gamma-32P]GTP to EF-2 was significantly reduced upon ADP-ribosylation. ADP-ribosylation almost abolished both the stimulatory effect of ribosomes on GTP binding to EF-2 and the ability of EF-2 to form a high-affinity complex with GuoPP(CH2)P and ribosomes. Low-affinity complex formation between EF-2 X GDP and ribosomes was not influenced by ADP-ribosylation. The results indicate that the inhibition of the elongation process caused by the toxin is probably due to the inability of modified EF-2 to exchange GDP with GTP.
mesh_terms: D000246:Adenosine Diphosphate Ribose / Q000378:metabolism*; D004167:Diphtheria Toxin / Q000378:metabolism*; D006150:Guanine Nucleotides / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D066298:In Vitro Techniques; D020652:Peptide Elongation Factor 2; D010445:Peptide Elongation Factors / Q000378:metabolism*; D012270:Ribosomes / Q000378:metabolism*; D014908:Triticum
chemical_list: D004167:Diphtheria Toxin; D006150:Guanine Nucleotides; D020652:Peptide Elongation Factor 2; D010445:Peptide Elongation Factors; D000246:Adenosine Diphosphate Ribose; D006160:Guanosine Triphosphate