H3.3 is expressed throughout the cell cycle, in contrast to most histones that are expressed during S phase during replication.

TLS Online TPP Program

#Id: 8936

#Unit 2. Cellular Organization

When a kinetochore is unattached, the outer kinetochore component Knl1 is phosphorylated by the checkpoint kinase Mps1.

TLS Online TPP Program

#Id: 8937

#Unit 2. Cellular Organization

Phosphorylated Knl1 binds the checkpoint protein kinase Bub1-Bub3 and checkpoint protein BubR1. These three proteins, recruit the Mad1-Mad2 complex to the kinetochore.

TLS Online TPP Program

#Id: 8938

#Unit 2. Cellular Organization

The Mad1-Mad2 complex bound to a kinetochore adopts the active closed form (Mad2-C) and has the ability to convert inactive open Mad2 (Mad2-O) in the cytoplasm into active closed Mad2 is able to inhibit APC/Ccdc²⁰

TLS Online TPP Program

#Id: 8939

#Unit 2. Cellular Organization

checkpoint factors Bub1-Bub3, BubR1 and Mad2-C Together, these proteins form the mitotic checkpoint complex

TLS Online TPP Program

#Id: 8940

#Unit 2. Cellular Organization

Knl1 eliminating checkpoint protein binding sites at kinetochores. p31comet disassembles the MCC, allowing APC/Ccdc20 to degrade mitotic cyclins and securin to trigger anaphase.

TLS Online TPP Program

#Id: 8941

#Unit 2. Cellular Organization

Spindle position checkpoint pathway ensures that the nucleus is accurately partitioned between two daughter cells