Fig. 11. Comparison of the mammalian SRF–TCF and yeast Mcm1–Fkh2 complexes. The yeast Mcm1–SFF complex is very similar to the mammalian SRF–TCF complex. Both complexes contain winged helix–turn–helix proteins, the forkhead protein (Fkh2) and the ETS-domain protein (TCF). In addition, Fkh2 and TCF are recruited to promoters by the highly related MADS-box proteins Mcm1 and SRF. Furthermore, Fkh2 (see previously) and TCF (Treisman, 1994) are modified by phosphorylation. Indeed, there are numerous S/TP motifs in the C-terminal region of Fkh2, which is highly reminiscent of TCF’s structure. Although the SRF–TCF complex is thought to function to promote cell cycle entry, while the Mcm1–Fkh2 complex regulates cell cycle expression in G₂/M, these similarities suggest that the activity of these complexes may be regulated in a similar manner.