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.