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Elongation factors are a set of proteins that function at the ribosome, during protein synthesis, to facilitate translational elongation from the formation of the first to the last peptide bond of a growing polypeptide.
Multiple classical translation factor family GTPases play important roles in initiation, elongation and termination of protein biosynthesis. Sharing a similar mode of ribosome binding due to the β-EI domain following the GTPase, the most well-known members of the family are EF-1A / EF-Tu , EF-2 / EF-G , [ 9 ] and class 2 release factors .
One of the elongation factors, P-TEFb, is particularly important. [25] P-TEFb phosphorylates the second residue (Ser-2) of the CTD repeats (YSPTSPS) of the bound Pol II. P-TEFb also phosphorylates and activates SPT5 and TAT-SF1. SPT5 is a universal transcription factor that helps recruit 5'-capping enzyme to Pol II with a CTD phosphorylated at ...
P-TEFb mediates a transition into productive elongation by phosphorylating the two negative factors and the polymerase and is regulated by association with the 7SK snRNP. The positive transcription elongation factor, P-TEFb , is a multiprotein complex that plays an essential role in the regulation of transcription by RNA polymerase II (Pol II ...
Elongation depends on eukaryotic elongation factors. At the end of the initiation step, the mRNA is positioned so that the next codon can be translated during the elongation stage of protein synthesis. The initiator tRNA occupies the P site in the ribosome, and the A site is ready to receive an aminoacyl-tRNA. During chain elongation, each ...
When all σ-factor is present, RNA polymerase is in its active form and is referred to as the holoenzyme. When the σ-factor detaches, it is in core polymerase form. [4] [1] The σ-factor recognizes promoter sequences at -35 and -10 regions and transcription begins at the start site (+1). The sequence of the -10 region is TATAAT and the ...
Once translation initiation is complete, the first aminoacyl tRNA is located in the P/P site, ready for the elongation cycle described below. During translation elongation, tRNA first binds to the ribosome as part of a complex with elongation factor Tu or its eukaryotic or archaeal counterpart. This initial tRNA binding site is called the A/T site.
EF-G (elongation factor G, historically known as translocase) is a prokaryotic elongation factor involved in mRNA translation. As a GTPase , EF-G catalyzes the movement (translocation) of transfer RNA (tRNA) and messenger RNA (mRNA) through the ribosome .