The Mad2 spindle checkpoint protein undergoes similar major conformational changes upon binding to either Mad1 or Cdc20.
Mad2 participates in spindle checkpoint inhibition of APC(Cdc20). We show that RNAi-mediated suppression of Mad1 function in mammalian cells causes loss of Mad2 kinetochore localization and impairment of the spindle checkpoint. Mad1 and Cdc20 contain Mad2 binding motifs that share a common consensus. We have identified a class of Mad2 binding peptides with a similar consensus. Binding of one of these ligands, MBP1, triggers an extensive rearrangement of the tertiary structure of Mad2. Mad2 also undergoes a similar striking structural change upon binding to a Mad1 or Cdc20 binding motif peptide. Our data suggest that, upon checkpoint activation, Mad1 recruits Mad2 to unattached kinetochores and may promote binding of Mad2 to Cdc20.
Luo
Xuelian
X
Department of Biochemistry, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA.
Tang
Zhanyun
Z
Rizo
Josep
J
Yu
Hongtao
H
D002135:Calcium-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D064199:Cdc20 Proteins; D018797:Cell Cycle Proteins; D006367:HeLa Cells; D006801:Humans; D008024:Ligands; D064246:Mad2 Proteins; D008958:Models, Molecular; D009687:Nuclear Proteins / Q000737:chemistry / Q000378:metabolism; D010750:Phosphoproteins / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry / Q000378:metabolism*; D012097:Repressor Proteins / Q000737:chemistry / Q000378:metabolism*
D002135:Calcium-Binding Proteins; D064199:Cdc20 Proteins; D018797:Cell Cycle Proteins; D008024:Ligands; C501384:MAD1L1 protein, human; C577697:MAD2L1 protein, human; D064246:Mad2 Proteins; D009687:Nuclear Proteins; D010750:Phosphoproteins; D011506:Proteins; D012097:Repressor Proteins; C577488:CDC20 protein, human