Fig. 3.

The SARS‐CoV‐2 spike C‐tail binds the COPI β’ subunit. (A) The indicated cytoplasmic C‐tails were cloned downstream of GST and expressed and purified from bacteria. (B) HEK293 whole‐cell lysate (input) was incubated with WT SARS‐CoV‐2 spike tail or GST, to control for nonspecific binding. Proteins in the pellet fraction were immunoblotted for endogenous COPβ and COPδ subunits and the monomeric clathrin adaptor GGA2. (C) GST pull‐downs were performed similar to (B) except HEK293 cells were transfected with either full‐length, human COPβ’‐myc, or COPα‐myc before preparing whole‐cell lysate. Blots were probed with anti‐myc antibody. (D) GST pull‐downs performed similar to (B) except using Sf9 insect cell lysates expressing COPI hemicomplexes β‐HA/δ (probed with anti‐HA) or γ1‐Flag/ζ1 (probed with anti‐Flag), or COPε‐ProtC alone. (E &F) GST pull‐downs performed using Sf9 insect cell lysates expressing the clathrin adaptor hemicomplexes AP‐1 γ1‐HA/σ1 (probed with anti‐HA), AP‐2 α‐HA/σ2 (probed with anti‐HA), or AP‐1 β1/µ1 (probed for µ1). (G) GST pull‐downs performed similar to C with other viral spike tails and probed with anti‐myc antibody.