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SATURNINO HERRERO Y COLS. AN. R. ACAD. NAC. FARM.

FIGURE 1. A, the 619 amino acid wild type HRI sequence is illustrated by a large
box and shown at the top. The black boxes represent the conserved two lobes of

the eIF2a kinase domain, separated by a large insert region (stippled boxes)
between subdomains IV and V. Position of the two heme regulatory motifs (HRM1

and 2) within the catalytic domain is shown. Six generated mutants are shown:
HRI C409A/C550A (in which the conserved cysteines in both HRM1 and HRM2
are mutated to alanine); HRI ?137/C409A/C550A (previous mutant in which the
first 137 amino acids were deleted); HRI 138-580/C409A/C550A (previous mutant

with the indicated deletion at the C-terminus); HRI ?8 (an eight-amino acid
deletion in HRM1); HRI ?8/C550A (mutant containing HRM1 deletion and C550A
substitution); HRI Q4 (in which the insert region of HRI kinase was replaced by

the corresponding insert region from mouse GCN2). The numbers refer to the
amino acid residues. B, the five domains of mouse HRI included the N-terminus

(N); the conserved two lobes of the eIF2a kinase domain separated by a large
insert (amino acids 236-373); and the C-terminus (C) are indicated. The 11
invariant residues and the two HRMs, within the eIF2a kinase domain, that are

absent in other Ser/Thr protein kinases are also indicated.

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