The cooperative function of arginine residues in the Prototype Foamy Virus Gag C - terminus mediates viral and cellular RNA encapsidation. (dresden-ipp.de)
While Class I binds via interactions mediated by backbone hydrogen bonds, Class II uses a pair of arginine residues to establish salt bridges to its ATP ligand. (journals.plos.org)
McsB, a protein involved in this process, turned out to have a unique ability to phosphorylate other proteins on arginine residues. (sciencedaily.com)