Figure 4.

A potential binding site on SCF for c-kit and a model of SCF⋅SCFR complex. (A) Molecular surface of SCF and proposed c-kit binding regions, in two views related by a rotation of approximately 90°. A hydrophobic crevice at both tails is colored yellow. Two basic patches are colored blue, and the acidic patch is colored red. (B) Sequence alignments of human, rat, mouse, dog, and pig SCFs. Residues of the acidic patch are colored red and residues of the two basic patches are colored blue. Asterisks mark amino acid residues that are altered in rodents. The secondary structures (SS) are marked below the sequences with H representing helices and E representing β-strands. (C) Proposed model of the SCF in complex with Ig-like domains 2–5 of the extracellular domain of c-kit (labeled D2 to D5). SCF dimer is represented in a worm model, and the c-kit model is represented by a molecular surface.