Three classes of myosins:

Myosin I

Myosin II

Myosin V

TLS Online TPP Program

#Id: 8857

#Section 3: Genetics, Cellular and Molecular Biology

The ATPase domains interact with the proteins

Scc1 and Scc3, which together form a cohesin ring structure which embrace one or both copies of the replicated DNA.

TLS Online TPP Program

#Id: 8858

#Section 3: Genetics, Cellular and Molecular Biology

Cohesin-mediated cohesion between sister chromatids is established by a two-step process:

1.Loading and unloading of cohesins

2. Stabilization of cohesins

TLS Online TPP Program

#Id: 8859

#Section 3: Genetics, Cellular and Molecular Biology

During G1, 

cohesins associate with chromosomes by cohesin loading factors Scc2 and Scc4 and unloaded continuously by a cohesin associated complex Pds5 and Wap1 proteins. 

TLS Online TPP Program

#Id: 8860

#Section 3: Genetics, Cellular and Molecular Biology

During S phase

DNA-bound G1 cohesins Convert into cohesive complexes by cohesin acetyl transferases (CoATs)

which acetylate Smc3 subunit & prevents unloading of cohesins by Pds5-Wapl, thereby stabilizing the cohesins on chromosomes.

TLS Online TPP Program

#Id: 8862

#Section 3: Genetics, Cellular and Molecular Biology

In vertebrates, stabilization of cohesins requires the cohesin-associated factor sororin.

TLS Online TPP Program

#Id: 8864

#Section 3: Genetics, Cellular and Molecular Biology

Defects of cohesin’s gene expression regulation function are the cause of a group of diseases collectively called cohesinopathies.