Expression and visualization of D assemblies. (A) D1 or D4 constructs. Cysteines are shown in vertical lines, and are connected for known and predicted disulfide bonds. (B) Expression of constructs by transient HEK293S GntI⁻ transfectants as measured by Western blotting with anti-His tag of equal quantities of supernatants subjected to SDS 10% PAGE. (C) Superdex 200 gel-filtration of purified D1 (23-385) and D4(1873-2255) in 20mM Bis-Tris, pH 6.2, 0.15M NaCl, and 10mM CaCl₂. Elution positions of calibration proteins are marked. (D) SDS-PAGE of D1 and D4 constructs with and without endoglycosidase H treatment stained with Coomassie blue. (E) Raw EM image of D4(1873-2255) in 20mM Bis Tris, pH 6.2, 0.15M NaCl, and 10mM CaCl₂. (F) Representative class averages of D4(1873-2255). (G) Comparison between class averages of D4-CK head (aligned with a radius of 12 nm) and D4 (1873-2255). (H) Representative class averages of D1 (23-385) monomers at pH 6.2. (I) Raw EM image of D1-D2 (23-763) in 20mM HEPES, pH 7.4, and 0.15M NaCl. (J) Representative class averages of D1-D2. Scale bars represent 50 nm in raw images and 5 nm in class averages.