Elongation factor Tu (EF-Tu) is a GTPase that delivers aminoacyl-tRNA (aa-tRNA) to the ribosome during protein synthesis. The factor is activated in response to the correct recognition of the mRNA codon by the anticodon of the aa-tRNA. The mechanism of signalling between the decoding centre of the ribosome and the site of GTP hydrolysis in EF-Tu where GTP hydrolysis takes place is not known. New high-resolution cryo-electron microscopic (cryo-EM) structures of the ribosome complex with aa-tRNA and EF-Tu blocked by the antibiotic kirromycin provide insights into the mechanistic details of the long-range signalling responsible for GTPase activation
