Gag/pol translational readthrough site

Gag/pol translational readthrough site (or Retroviral readthrough element) is a cis-regulatory element found in retroviruses.{{cite journal |vauthors=Wills NM, Gesteland RF, Atkins JF |title=Pseudoknot-dependent read-through of retroviral gag termination codons: importance of sequences in the spacer and loop 2 |journal=EMBO J. |volume=13 |issue=17 |pages=4137–4144 |date=September 1994 |doi=10.1002/j.1460-2075.1994.tb06731.x |pmid=8076609 |pmc=395336 }} The readthrough site facilitates the mechanism of translation readthrough of the stop codon at the gag-pol junction producing the gag and pol fusion protein in certain retroviruses.

Retroviruses whose gag and pol genes are in the same reading frame often depend upon approximately 5% read-through of the gag UAG termination codon to form the gag-pol polyprotein. This readthrough is usually dependent on a pseudoknot located eight nucleotides downstream of the stop codon (UAG). Sequence conservation is found in the second pseudoknot loop.

File:GP_knot1_secondary_structure.jpg|GP_knot1Family [http://rfam.org/family/RF01073 RF01073]. Derived from Pseudobase [http://www.ekevanbatenburg.nl/PKBASE/PKB00047.HTML PKB00047] [http://www.ekevanbatenburg.nl/PKBASE/PKB00078.HTML PKB00078] [http://www.ekevanbatenburg.nl/PKBASE/PKB00079.HTML PKB00079] [http://www.ekevanbatenburg.nl/PKBASE/PKB00088.HTML PKB00088] [http://www.ekevanbatenburg.nl/PKBASE/PKB00098.HTML PKB00098] [http://www.ekevanbatenburg.nl/PKBASE/PKB00099.HTML PKB00099]

File:GP_knot2_secondary_structure.jpg|GP_knot2Family [http://rfam.org/family/RF01092 RF01092]. Derived from Pseudobase [http://www.ekevanbatenburg.nl/PKBASE/PKB00048.HTML PKB00048]