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. 2023 Apr 12;616(7958):764–773. doi: 10.1038/s41586-023-05927-7

Extended Data Fig. 15. Astrocyte subcompartment card 5: astrocyte potassium channel.

Extended Data Fig. 15

a. BioID2 that is targeted with Kir4.1-BioID2 biotinylates proteins at astrocyte sites of potassium uptake. b. Label-free based quantification comparison of significant proteins (Log2FC > 1 and FDR < 0.05 versus GFP controls) detected in the cytosolic Astro BioID2 and Astro Kir4.1-BioID2 reveal Kir4.1 enriched proteins. Top half of the volcano plot shows 390 unique Kir4.1-BioID2 proteins when compared to cytosol. The top four most abundant proteins for Kir4.1-BioID2 are shown. Lower half of volcano plot shows comparison of 275 proteins that were common in both cytosolic BioID2 and Kir4.1-BioID2. The five highest enriched proteins for Kir4.1-BioID2 are shown. Magenta label shows protein that was validated with immunohistochemistry. c. Heat map shows the rank-rank hypergeometric overlap (RRHO) of the RNA and protein rank for the 393 Kir4.1-BioID2 proteins. Each pixel represents the significance of overlap between the two datasets in –log10(P-value). Red pixels represent highly significant overlap. Color scale denotes the range of P-values at the negative log10 scale (Bin size = 100). d. IHC analysis of Hepacam protein in tdTomato and Kir4.1-GFP labeled astrocytes shows co-localization within the astrocyte territory. Scale bar represents 20 μm. e. Co-localization analysis using Pearson’s r co-efficient shows high co-localization between Kir4.1-GFP and Hepacam. The mean and SEM are shown (n = 8 tdTomato+ cells from 4 mice; Two-tailed paired t-test). f. Scale-free STRING analysis protein-protein association map of the top 100 unique and enriched biotinylated proteins identified with Astro Kir4.1-BioID2 . Node size represents the enrichment of each protein vs the GFP control (log2(BioID2/GFP)). Edges represent putative interactions from the STRING database. Bar graphs show the functional enrichment analysis of all 393 proteins using “Biological process”, “Cellular component”, and “Molecular function” terms from Enrichr. The image of the astrocyte subcompartments in panel a was created using BioRender (https://www.biorender.com/).