A molecular model of human SCF structure. The model is based extensively on the published structure of human M-CSF (Modified and reprinted with permission from Pandit et al.69 Copyright 1992 American Association for the Advancement of Science.) and the M-CSF/SCF alignment of Bazan.66 The SCF four helix bundle with two long overhand loops is shown as a ribbon diagram. The location of the two intramolecular disulfide bonds is shown in yellow, and the helix boundaries are indicated in the single amino acid code. The interhelical loop lengths have been altered from the M-CSF structure to account for the slightly longer predicted loops of SCF. Tyr26 may be part of the dimer interface for SCF; this residue corresponds to Cys31 of M-CSF, the site of the single M-CSF interchain disulfide bond (Cys31-Cys31 ).
