eIF2B binds GTP
(A) Purified eIF2B (Figure S1A) binds radiolabeled GTP in a concentration-dependent manner. Increasing concentrations of eIF2B bind 32PGTP; BSA was used as a control.
(B) GTP binding by eIF2B increases over time. Error is shown as standard error of the mean (s.e.m).
(C) Both eIF2Bγ and ε are required for binding of GTP. GTP binding is expressed relative to eIF2B complexes (12 μmol of each protein used), and error is shown as s.e.m of ≥3 technical replicates.
(D) Competition binding assays with indicated excess concentrations of unlabeled ATP or GTP. Error as panel B.
See also Figure S1.