Extended Data Fig. 6: Structural details of receptor–cytokine and receptor–receptor interactions in ALK/LTK–cytokine complexes.
From: Structural basis of cytokine-mediated activation of ALK family receptors
a, 2Fo-Fc electron density maps contoured at +1 r.m.s.d. showing details of site 1, 2 and 3 of the LTK—ALKAL1 and ALK—ALKAL2 complexes. b, Transparent surface of ALKAL1 according to the Eisenberg hydrophobicity scale illustrating similarities and differences in site 1 of LTK/ALK–cytokine complexes. Shown is the central conserved hydrophobic patch formed by leucines (L97, L116 and L120) and the interacting residues of LTK (orange). The equivalent ALK residues (pink) are shown after alignment with LTK. c, View of Site 2 in the LTK—ALKAL1 and ALK—ALKAL2 complexes. ALKALs are coloured according to the Eisenberg hydrophobicity scale. Receptor residues surrounding the hydrophobic triad of helix A (L72, F76, F80 in ALKAL1 and M93, F97, L101 in ALKAL2) are shown as sticks for LTK (orange) and ALK (pink). d, Superposition of unbound ALK (dark gray), unbound LTK (light gray), bound ALK (pink, only helices shown) and bound LTK (orange, only helices shown). e, Superposition of the ALK—ALKAL2 and LTK—ALKAL1 complexes, zoomed in on the region around the e-f loop. f, View of the site 3 groove of ALK (top) and LTK (bottom). In LTK, site 3 centers on His153, which stacks against Gly74 and Arg241 on an LTK-specific loop with Asn369 residues hydrogen bonding across the twofold axis of the complex.
