<p><b>A,</b> Arch model of Fks1p indicating the positions of BS3 (red) XLs visualized using xVis. <b>B,</b> topology model of Fks1p proposed using the crosslinking data to validate a topology prediction visualized by Protter [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0186840#pone.0186840.ref019" target="_blank">19</a>].</p