IDRs in nucleolar localization.

(A) Model of the 3 nucleolar subdomains or compartments. (B) Biological variation of wild-type Ncl-GFP co-expressed with Fbl-mRed, shown as expressed in four different frogs, showing that Ncl is always in the GC and sometimes spreads into the DFC. (C) Schematic of the protein fusions shown in D-F. Each of these fusions also contains a green or red fluorescent protein as indicated in B that allowed detection. The IDR-Ncl has a net negative charge of −40, the IDR-Fbl has a net positive charge of +17, and the N terminal IDR-Gar1 has a net positive charge of +7. (D–F) Representative images of nucleoli with IDR chimera proteins fused with a fluorescent protein co-expressed with a DFC nucleolar domain marker (Fbl). (D) Representative images showing the intrinsically disordered regions of Fbl (IDR-Fbl-GFP) and Ncl (IDR-Ncl-GFP) co-expressed with Fbl-mRed. (E) Representative images showing the fusions of IDR-Ncl and Fbl, showing IDR-Ncl-Fbl-eGFP, IDR-Ncl-ΔNFbl-eGFP, and ΔNFbl-eGFP all co-expressed with Fbl-mRed. *IDR-Ncl-Fbl-eGFP images were taken at a lower exposure in the green channel due to it being far brighter than the other constructs in this set. (F) Representative images showing the fusions of IDR-Ncl and Gar1, showing the localization of Gar1-mCherry (WT that localizes to the DFC), IDR-Ncl-Gar1-mCherry, IDR-Ncl-ΔNGar1-mCherry, and ΔNGar1-mCherry all co-expressed with Fbl-eGFP. Scale 10 μm. Statistical analysis is shown in S1 Fig and S2 Data. DFC, dense fibrillar component; IDR, intrinsically disordered region.