Final answer:
EF-Ts is the guanine nucleotide exchange factor (GEF) that recycles EF-Tu by replacing GDP with GTP, allowing it to participate again in the elongation cycle of protein synthesis. The other factors listed (EF-G, IF-3, IF-2) have different roles in various stages of translation.
Step-by-step explanation:
The function of guanine nucleotide exchange factors (GEFs) in protein synthesis is to facilitate the exchange of GDP for GTP on proteins that require GTP to function. Specifically, in the context of translation elongation, this question concerns which factor recycles EF-Tu by replacing GDP with GTP. EF-Ts is the correct answer as it acts as a GEF for EF-Tu, enabling it to re-enter the elongation cycle with a fresh molecule of GTP.
The other factors mentioned (EF-G, IF-3, and IF-2) have distinct functions during different stages of the translation process. EF-G is involved in the translocation step of elongation, IF-3 is involved in the initiation phase to prevent premature binding of ribosomal subunits, and IF-2 aids in the binding of the initiator tRNA to the ribosome during initiation.
Understanding the role of these factors and their regulation is crucial for maintaining the accuracy and efficiency of protein synthesis, which is essential for proper cell function and homeostasis.