Structural variability of POT1/TPP1/GFP-TIN2. (A) Domain schematics for POT1, TPP1, TIN2, and deletion constructs with amino acids are indicated. Coloring is as in Fig. 1A. In POT1 and TPP1 deletion constructs, dashed lines represent regions that have been replaced with (Gly-Gly-Ser)2. (B) Cartoon schematics for POT1/TPP1/GFP-TIN2 wild type (wt) and deletion construct (3×Δ) bound to telomeric ssDNA. (C) SDS-PAGE of purified wt and 3×Δ POT1/TPP1/GFP-TIN2. TS, Twin-Strep. Protein gel as in Fig. 1B. (D) Negative-stain EM analysis of wt and 3×Δ POT1/TPP1/GFP-TIN2 bound to streptavidin-5′-biotin-(GGTTAG)2 DNA. Reference-free 2D class averages that were directly comparable to those for POT1/TPP1N were selected for display with cartoon interpretations (Bottom). (E) Cross-linking MS of wt POT1/TPP1/GFP-TIN2 using BS3. Domains are shown and colored as in A and cross-links are shown as solid lines. Intramolecular cross-links are not shown.