Figure 1. CPR5 Is a Transmembrane Protein Enriched in the Nuclear Pore
(A and B) Subcellular localization of GFP-tagged CPR5 when transiently expressed inN. benthamiana. Wild-type (WT) CPR5 (A, left), the G420D mutant (A, right),
and WT CPR5 co-expressed with a mCherry-tagged marker labeling mitochondria and nucleoplasm (B) were shown. Images were obtained 24 hr post
Agrobacteriuminfiltration.
(C) CPR5 contains an evolutionarily conserved transmembrane (TM) region at the carboxyl terminus. Top: amino acid conservation map derived from multiple
sequence alignments of CPR5 proteins fromMicromonas pusilla,Chlorella variabilis,Physcomitrella patens,Sorghum bicolor,Selaginella moellendorffii,Vitis
vinifera,Populus tricocarpa,Ricinus communis,Oryza sativa,Zea mays, andArabidopsis thaliana. Middle: schematic of AtCPR5 domain structure with trans-
membrane TM domains (TMDs) predicted by TMpred. Arrowheads indicate sites of loss-of-function missense mutations. Bottom: liquid chromatography-
tandem mass spectrometry (LC-MS/MS) peptide coverage in the C-terminal half of AtCPR5 purified from transgenicArabidopsis. Predicted omissions were
calculated by PeptideMass for trypsin digestion (seeFigure S1C).
(D) Pearson’s correlation coefficients of co-localization between CPR5 and endomembrane organelle markers. WT CPR5 (blue dashed circles) co-localized with
both the nuclear envelope (NE) marker (WIT1) and ER-associated granules (seeFigure S1B). CPR5 with missense mutations in the TMDs (Mut) and sequential
truncations of individual TMDs (N + TM) all exclusively localized in tubular ER structures (magenta dashed circle). TGN (early endosome) and MVB (late endosome)
markers were used as a negative control (nc).
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