The central player in the “canonical” Wnt intracellular signal transduction pathway is called β-catenin.

TLS Online TPP Program

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#Unit 2. Cellular Organization

Mammalian H2ABbd variant is excluded from the inactive X and forms a less stable nucleosome than canonical H2A

TLS Online TPP Program

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#Unit 2. Cellular Organization

The nucleosome is 200 bp of DNA, organized by an octamer of small, basic histone proteins into a beadlike structure. 

TLS Online TPP Program

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#Unit 2. Cellular Organization

The nucleosome is of 10nm/100A diameter, compacting the DNA about 6-fold over the length of naked DNA. Its first level of organization. 200X3.4A=680A

TLS Online TPP Program

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#Unit 2. Cellular Organization

The second level of organization is the coiling of the 10-nm fiber of nucleosomes into a helical array to constitute the fiber of diameter 30 nm.

TLS Online TPP Program

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#Unit 2. Cellular Organization

30 nm compacts the DNA 40-fold. This structure of this fiber requires the histone tails and is stabilized by linker histones.

TLS Online TPP Program

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#Unit 2. Cellular Organization

This 30-nm fiber is further folded, results in 1000-fold compaction in euchromatin in interphase chromatin and in mitotic chromosomes to achieve an overall 10,000- fold compaction in euchromatin.