GMPS can form a quaternary complex with USP7, EBNA1 and DNA.

<p>The indicated combinations of EBNA1_395–641 , USP7 and GMPS were preincubated then combined with the DNA containing the EBNA1 recognition site and EMSAs were performed as in <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1000624#ppat-1000624-g002" target="_blank">Figure 2C</a>. Excess amounts of USP7 alone or USP7 and GMPS were used relative to EBNA1_395–641. In lane 6, the USP7-EBNA complex was preformed prior to the addition of GMPS then DNA. The positions of complexes formed by EBNA1 alone, EBNA1+USP7 and EBNA1+USP7+GMPS are indicated by arrowheads 1, 2 and 3 respectively. DNA incubated with the same amounts of GMPS, USP7 or GMPS+USP7 but in the absence of EBNA1 are also shown (lanes 8–10).