Chromodomains read the arginine code of post-translational targeting

Nuclear chromodomain-containing proteins read the epigenetic code by recognizing methylated lysine residues in histone tails. Structural analysis of the cytoplasmic chloroplast signal recognition particle subunit cpSRP34 in complex with the cpSRP54 subunit C-terminal tail comprising an arginine-rich motif reveals that a twinned aromatic cage reads two neighboring nonmethylated arginine residues and adapts chromodomains to a function outside the nucleus.