Extended Data Fig. 3: Comparison of ArfR and eukaryotic Arf family sequences.
From: The Asgard archaeal origins of Arf family GTPases involved in eukaryotic organelle dynamics
a, Sequence alignment of HodArfR1 and GerdArfR1 with three eukaryotic Arf proteins (Homo sapiens Arf1, HsArf1, Homo sapiens Arl8A, HsArl8A and Leishmania major Arl1, LmArl1). These representatives were chosen because of structural data available (GDP-bound forms with the N-terminal AH present, in addition to the GTP-bound forms), and because they have different properties, representing the wide range of Arf family proteins in eukaryotes. The N-terminal AH is highlighted in yellow with the glycine at position 2 in black. Switch I and Switch II are highlighted in dark grey and the interswitch in light grey. The G (guanine-binding) motifs are indicated in bold and underlined. The S/T residue that (mutated to N in the dominant negative) and the Q (mutated to L in the constitutively active) mutants are indicated in red and green, respectively. Other highly conserved residues, invariant among the GTPases shown here, are indicated in black. AH, amphipathic helix; SwI, Switch I; iSw, interswitch region; SwII, Switch II. b, Helical wheel representations generated by Heliquest79 of the N-terminal AHs of the ArfR and eukaryotic Arf family sequences shown in part a). Color code for the amino acids is yellow: Val, Leu, Ile, Met, Phe, and Trp, pink: Ser and Thr, red: Asp and Glu, blue: Lys and Arg, grey: other residues. Size of letter for each amino acid in the helical wheel representation is proportional to amino acid volume; downward pointing arrow represents the helical hydrophobic moment <µH > , with length proportional to the calculated value and direction indicating that the helix is amphipathic in the perpendicular direction.
