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. Author manuscript; available in PMC: 2024 Apr 24.
Published in final edited form as: Annu Rev Biomed Data Sci. 2022 Apr 26;5:67–94. doi: 10.1146/annurev-biodatasci-121721-095858

Figure 5. RNA granules and cytoplasmic condensates in the eukaryotic cell.

Figure 5.

A. Following stress, mRNAs partition to P-bodies and stress granules where they are degraded or stored, respectively. Assemblysome: Following arsenite stress, mRNAs encoding proteasomal subunits Rpt1 and Rpt2 co-localize in granules enriched in Not1p/CNOT1 proving a protected environment. Under unstressed conditions we find: Transperons: The chromosomal rearrangement and concerted transcription of genes encoding functionally related mRNAs form cytoplasmic condensates. Translation factory: Translation competent cytoplasmic condensate that harbor homotypic or heterotypic mRNAs. TIS granule: The RBP TIS11B forms an intricated condensate intertwined with the ER that facilitates 3’UTR-mediated protein-protein interactions and protein complex formation. SRP preloading: SRP preloads specific ribosomes translating mRNAs before any SS or TMTs domain has emerged from the ribosome. Once in the ER membrane, a pioneering round of translation is complete, further rounds of translation initiation and elongation occur. B. RBPs serve as a hub for protein complex assembly. Homotypic interactions within RBPs form the condensate, and heterotypic interactions allow interactions of fully folded proteins that enrich locally in the condensate (Chen and Mayr, 2021) C. Models of co-co assembly of heteromers in the eukaryotic cell within condensates harboring mRNAs encoding protein complex subunits: A cytoplasmic condensate favor protein complex assembly peri-translationally from where fully assembled complexes are ejected into the cytoplasm. Alternately, mRNAs could find each other in the cytoplasm in a pioneer round via nascent chain interactions facilitating the assembly of the granule. Further rounds of translation would facilitate the synthesis of new protein complexes locally. D. Model of co-co assemble of homomers in the eukaryotic cell: independent and homotypic mRNA condensates facilitate the assembly of homomers. In the diagram, ENO1 and ENO2 independent yeast granules presumably would impede the formation of heteromers by spatially sequestration of mRNAs in independent granules (Morales-Polanco et al., 2021)