In this 1st step, the corresponding aminoacyl-tRNA for the second codon binds to the A site by codon-anticodon interaction. Binding of the aminoacyl-tRNA needs elongation factor EF-Tu and GTP that bind as an aminoacyl-tRNA/EF-Tu/GTP complex. Subsequent binding, the GTP is hydrolyzed and the EF-Tu is released, now bound to GDP. Before the EF-Tu molecule can catalyze the binding of one another charged tRNA to the ribosome, it have to be regenerated by a process including another elongation factor, EF-Ts. This regeneration is called as the EF-Tu-EF-Ts replace cycle. First, EF-Ts bind to EF-Tu and show the GDP. Then GTP binds to the EF-Tu and shows EF-Ts. An EF-Tu-GTP is now prepared to take part in another round of elongation.