The positively charged region (loop 42–50) of uL14 that is buried into the ribosome for interacting with 25S rRNAs is protected by Bcp1 and Rkm1. (A) Compare the uL14 interaction within the pre-60S and Rkm1/Bcp1 complex. Left: uL14 was shown in 60S subunits, and the surrounded 25S rRNA was shown in gray. PDB accession no. 5H4P. Middle: uL14 was shown with Bcp1 and Rkm1. Right: The extension loops of uL14 were shown. (B) The growth complementation assays of the uL14∆loop and uL14(RA). (C) The interactions between recombinant Bcp1 and uL14 mutants were tested with Ni-NTA beads. (D) The interactions between Rkm1 and uL14 and uL14(Δloop) were examined in vitro. (E) Bcp1-myc, Tif6-myc, and Rkm1-myc were immunoprecipitated in the wild-type strain using protein A-coupled beads. The associated uL14 mutants were examined with the anti-HA antibody. Anti-eL8 antibody was used to probe 60S subunits. (F) The SET domain of Rkm1 was labeled in yellow, and the residues at the active site (red circle) were labeled in red. K106 and K110 were also shown on the uL14. (G) The model relaxation by molecular dynamics simulation shows the dynamic movement of this ternary complex at two states. The Lys106 and Lys110 residues of uL14 (blue circle) move to the Rkm1 active site (red circle) for methylation. Rkm1: pink; Bcp1: green; uL14: blue. (Please see Video 1 for the animation). Source data are available for this figure: SourceData F4.