Post-transcriptional repressor. May recognize and bind to the 3'-UTR of some mRNAs and promote mRNA decay. S-ubiquitinyl-[E2 ubiquitin-conjugating enzyme]-L-cysteine + [acceptor protein]-L-lysine = [E2 ubiquitin-conjugating enzyme]-L-cysteine + N(6)-ubiquitinyl-[acceptor protein]-L-lysine. Protein modification; protein ubiquitination. During cell stress, localizes to cytosolic stress granules. The RING-type zinc finger is required for proper localization to stress granules, but not to P-bodies. The ROQ region is required for CDE RNA-binding. It may also be involved in localization to stress granules. HEPN (higher eukaryotes and prokaryotes nucleotide-binding) are observed in both N- and C-terminal sides of ROQ domain with 3D structure even if they are poredcted on the basis of sequence. Proteolytically cleaved after Arg-509 and Arg-576 by MALT1 in activated CD4(+) T cells; cleavage at Arg-509 and Arg-576 is critical for promoting RC3H1 degradation in response to T-cell receptor (TCR) stimulation, and hence is necessary for prolonging the stability of a set of mRNAs controlling Th17 cell differentiation.