Final answer:
The molecule required to catalyze the GDP-GTP swap on eIF2 is a Guanine nucleotide exchange factor (GEF), which facilitates the transition necessary for continued protein synthesis.
Step-by-step explanation:
The molecule required to catalyze the GDP-GTP swap (dissociate GDP and eIF2) is a Guanine nucleotide exchange factor (GEF). GEFs facilitate the release of GDP from a GTP-binding protein, allowing GTP to bind and activate the protein. This process is essential in various cellular functions including protein synthesis, where GTP acts as an energy source during the initiation and elongation phases of translation. In the specific context of translation, eIF2 is a GTP-binding protein that, when in its GTP-bound form, can form an initiation complex with the ribosome and the methionine initiator tRNA to begin protein synthesis. However, once GTP is hydrolyzed to GDP, the eIF2-GDP complex must be recycled back to an eIF2-GTP form to continue protein synthesis, a step that requires GEF activity.