Figure 8.

Model for Cell Cycle Regulation by a Stable Nuclear MAT3/RB-E2F1-DP1 Complex.

(A) MAT3/RB actively represses the cell cycle in pre-Commitment cells while bound to E2F1-DP1, potentially through the recruitment of other repressor proteins signified by protein X. Phosphorylation of MAT3/RB is indicated by gray P symbols.

(B) MAT3/RB-E2F1-DP1 become modified or primed after Commitment, potentially by phosphorylation and/or loss of corepressors.

(C) A conformational change in MAT3/RB-DP1-E2F1 occurs during S/M that allows recruitment of cell cycle activators signified by protein Y binding to E2F1. The conformational change in MAT3/RB may be caused by further phosphorylation during S/M.