EF-G

EF-G or elongation factor G (historically known as translocase) is a prokaryotic elongation factor and a GTPase responsible for catalyzing the coordinated movement of tRNA and mRNA through the ribosome.

Function

The factor EF-G catalyzes the translocation of the tRNA and mRNA down the ribosome at the end of each round of polypeptide elongation. Just like the EF-Tu+tRNA+GTP complex, EF-G binds to the ribosome in its GTP-bound state. When it binds to the ribosome A-site, EF-G causes the tRNA previously occupying that site to occupy an intermediate A/P position (bound to the A site of the small ribosomal subunit and to the P site of the large subunit), and the tRNA in the P site is shifted to a P/E hybrid state. EF-G hydrolysis of GTP causes a conformation change that forces the A/P tRNA to fully occupy the P site, the P/E tRNA to fully occupy the E site (and exit the ribosome complex), and the mRNA to shift three nucleotides down relative to the ribosome due to its association with these tRNA molecules. The GDP-bound EF-G molecule then dissociates from the complex, leaving another free A-site where the elongation cycle can start again.

Boeing EA-18G Growler

The Boeing EA-18G Growler is an American carrier-based electronic warfare aircraft, a specialized version of the two-seat F/A-18F Super Hornet. The EA-18G replaced the Northrop Grumman EA-6B Prowlers in service with the United States Navy. The Growler's electronic warfare capability is primarily provided by Northrop Grumman. The EA-18G began production in 2007 and entered operational service in late 2009.

Development

Requirement and testing

On 15 November 2001, Boeing successfully completed an initial flight demonstration of F/A-18F "F-1" fitted with the ALQ-99 electronic-warfare system to serve as the EA-18 Airborne Electronic Attack (AEA) concept aircraft. In December 2003, the US Navy awarded a development contract for the EA-18G to Boeing. As primary contractor, Boeing was to construct the forward fuselage, wings and perform the final assembly. Northrop Grumman was the principal airframe subcontractor and they would supply the center and aft fuselage as well as the principal electronic combat system. In 2003, the Navy expected to receive 90 EA-18Gs.