What is eIF2B commonly known as?

eIF2B is commonly known as a guanine nucleotide exchange factor (GEF). Its primary role is to facilitate the exchange of GDP for GTP on the eIF2 protein, which is crucial for the initiation of translation in eukaryotic cells. When eIF2 is bound to GDP, it is inactive and cannot participate in the translation process. eIF2B promotes the release of GDP, allowing GTP to bind in its place, thus reactivating eIF2 for its role in initiating translation by helping to load the initiator tRNA onto the ribosome.

This enzymatic function is essential, as the availability of active eIF2 directly impacts the efficiency of translation initiation. By enhancing the concentration of active eIF2-GTP, eIF2B plays a critical role in regulating protein synthesis in response to various cellular signals and conditions. The other options describe different types of proteins involved in cellular processes, but they do not accurately represent the specific function of eIF2B as a guanine nucleotide exchange factor.