eIF2gamma

eIF2gamma refers to the gamma subunit of eukaryotic translation initiation factor 2 (eIF2). eIF2 is a crucial heterotrimeric protein complex that plays a pivotal role in the initiation of protein synthesis in eukaryotes. It is composed of three distinct subunits: alpha, beta, and gamma. The gamma subunit, encoded by the EIF2G gene, is the GTPase effector domain of the complex. This domain is responsible for binding and hydrolyzing guanosine triphosphate (GTP), a process that is essential for the regulated function of eIF2.

The primary function of eIF2 is to mediate the binding of the initiator methionine-tRNA (Met-tRNAi) to the 40S ribosomal subunit. This ternary complex, consisting of eIF2, GTP, and Met-tRNAi, then scans the messenger RNA (mRNA) for the start codon. Upon locating the start codon, the gamma subunit hydrolyzes GTP to guanosine diphosphate (GDP). This GTP hydrolysis triggers a conformational change in the eIF2 complex, leading to the release of GDP and inorganic phosphate, and facilitating the joining of the 60S ribosomal subunit to form the functional 80S initiation complex. The release of GDP from eIF2 is a critical step that allows the recycling of eIF2 for subsequent rounds of translation initiation. Dysregulation of eIF2 function, and consequently eIF2gamma activity, can have significant implications for cellular homeostasis and is implicated in various diseases.