lo 2 2. How do CTCF and Cohesin contribute to TAD formation?

What does CTCF stand for?

CCCTC-binding factor

How many zinc fingers does CTCF contain?

11 zinc fingers

How does the extended array of zinc fingers in CTCF contribute to its function?

Provides high specificity by coiling around the DNA helix

Where are CTCF binding sites typically located?

At TAD boundaries away from regulatory regions

Does CTCF bind to methylated DNA motifs?

No, CTCF binds to unmethylated motifs specifically

What happens to TADs when CTCF is depleted?

TAD formation is abrogated genome-wide

What are the ATPase subunits of the Cohesin complex?

SMC1A and SMC3

What happens when RAD21 (SCC1) is degraded?

Loss of chromatin architecture, TAD structure, and enhancer-promoter loops

What 3D contacts remain after RAD21 degradation?

Those governed by Polycomb complexes

What is the loop extrusion model?

The prevailing model for TAD formation

How do CTCF and Cohesin team up in loop extrusion?

DNA is pulled through Cohesin rings until CTCF boundaries are reached

What is the biological importance of TADs?

They create local compartments for regulatory interactions

What prevents enhancer-promoter contacts across TADs?

CTCF and Cohesin mediated spatial boundaries

Are TADs conserved between species?

Yes, 60-70% of TADs are conserved

Is CTCF found in all species?

No, CTCF is a Bilateria-specific gene