Fig. 1: Global architecture of the TCR–CD3 in detergent and nanodiscs.
From: The resting and ligand-bound states of the membrane-embedded human T-cell receptor–CD3 complex
a Nickel-nitrilotriacetic acid (NiNTA)-affinity purification scheme for TCR–CD3 in detergent (black lines) and its reconstitution into nanodiscs (red lines). b Backbone representations of GDN and prior TCR–CD3 structures (HLA not shown). c GDN model colored by sequence identity to the three TCR–CD3 complexes previously determined in detergent. Representative purification of nanodisc-embedded TCR–CD3, showing size-exclusion chromatogram (d; asterisk indicates peak), silver-stained SDS-PAGE (e; constituents identified by expected molecular weight, which does not distinguish CD3γ, δ, and ε), and negative-stain electron micrograph (f; inset, zoomed-in view). Colored asterisks in e indicate molecular weight values: magenta, 250 kDa; orange, 150 kDa; green, 100 kDa; white, 75 kDa; cyan, 50 kDa; yellow, 37 kDa; navy, 25 kDa. Data shown are representative of more than three experiments. g Cryo-EM maps (top, middle) and model surfaces (bottom) of TCR–CD3 in GDN and in nanodiscs. Top row shows B-factor-sharpened cryo-EM maps without local refinement, contoured to a low threshold to highlight micelle and nanodisc positioning. Red dashed box indicates approximate plasma membrane span (extracellular and intracellular faces indicated as e.c. and i.c., respectively). Middle row shows DeepEMhancer-sharpened maps after local refinement, accentuating the protein and glycan densities. Protein regions indicated at far right abbreviated as follows: var variable domains, ecto ectodomains, const constant domains, JM juxtamembrane linkers, TM transmembrane helices.
