DNA methylation - Histone variants
10 important questions on DNA methylation - Histone variants
What is a histone variant?
- encoded throughout the cell cycle, while standard are during S phase
Difference between canonical and variants?
- expressed during DNA replication
- deposited during DNA treplication
- encoded by multiple copies, in gene clusters
- Genes do not contain introns
- Transcripts non-polyadenylated
Histone variant:
- • Typically expressed throughout cell cycle
- • Typically deposited replication-independent • Encoded by individual genes
- • Genes typically contain introns
- • Transcripts usually polyadenylated
What are the function of some well-known variants?
CENP-A - centromere function and kinetochore assembly/ centromeric chromatin
H2AX - DNA repair and recombination
H2AZ - gene expression, chromosome segregation/ active/inactive chromatin
macroH2A - transcriptional repression, X-chromosoom inactivation/ inactive chromatin
- Higher grades + faster learning
- Never study anything twice
- 100% sure, 100% understanding
For my 1st exam I got a C. Then, I started looking for ways to learn better and I came across Study Smart. Since then I have scored a A+, A, A- and another A. I highly recommend it to everyone who wants to hear it. I am so happy with it!!
I was struggling to finish all my first-year subjects for 3 years. Then I discovered Study Smart, which helped me to finish all of them within 3 months.
Because of StudySmart, things are going well in many ways. Before, I always had study stress and no time for anything. Now I feel calm and confident (because of the program). I used to score a B, now I usually score an A or A+.
Hey Chris, I really want to thank you very much for developing the platform, I usually got around C for my exams, now I scored an A+, an A and a A- !!
Since using Study Smart, my average has increased significantly. I even completed a statistics course with a A+ while I'm bad at statistics. I took on extra courses this year, because of Study Smart. Thanks so much!
Ever since I started studying with StudySmart I passed all my exams !!! No more re-sits!! At first, I was happy with a pass and now I only get good grades. Many thanks!
I aced all the courses I studied with Study Smart. For law, I first scored a D, and now an A! I’m 100% sure that I’ll pass all the courses I study with Study Smart.
I always thought I studied well. My grades were fine. I could never have imagined that applying these study skills would have such a huge and direct impact on my grades, my speed and the pleasure I have in learning.
For the first time, I finally feel totally confident about the way I learn. I have the perfect overview and make great progress in terms of speed and the grades I get. Thanks, Chris!
I immediately started to enjoy learning again, and my grades soared. All of a sudden, everything went better. I highly recommend Study Smart to all students..
Being able to create my materials online made the process of studying so much smoother and quicker. I no longer have to spend a huge amount of my time on creating my summaries.
At first, my notes were a mess. Now I use Study Smart to take my notes in a perfectly structured way. It helps me to save a lot of time and do other things I enjoy.
Students that study with Study Smart get better grades. The system applies all the learning methods in such a way that both well-performing students and students who struggle perform much better.
Hi Chris, I would like to thank you very much. Last year I scored C on a course, and this year I got an A+ thanks to your method! Thank you very much!
The largest effect is that my child is more enthusiastic about school! Every parent wants their children to be happy at school, Study Smart made it happen.
In high school, I failed several exams, and that has really changed now. I actually needed this tool very much back then. Since I started studying with StudySmart, I haven't had any D's. My average score is now an A and those are results I would have never had in the past
With my old method, I passed only 3 out of 8 courses. Since I started taking my notes digitally in Study Smart, I have passed all my courses on the first try. For me, StudySmart takes away the stress of wondering if I will pass or not.
Thanks to StudySmart, I passed all my exams, and with better grades than before! On top of that, I have mastered a very good study method now, which I am confident will help me earn my degree.
What is the function of cenH3 (CENP-A)?
- CenH3 and H3 incorporation at centromeres alternate, and chromatin forms helical turns
What is the function of H3.3?
- Displaced H3 histones are replaced by H3.3 histones
- H3.3 prevents cryptic initiation of transcription!
- Most transcription occurs in genic regions: hence most H3.3 is incorporated into genic regions
Explain the difference between deposition of H3 and H3.3 into chromatin
H3.3 is deposited in a replication- independent manner (during & outside replication.
- HIRA histone chaperone deposits H3.3 at genes and regulatory sequences
- Daxx histone chaperone deposits H3.3 at repetitive DNA (heterochromatin)
Why is H3.3 also present at heterochromatin?
H3.3 is also present at a.o. telomeric repeats & pericentric heterochromatin (low levels)
- In repeated sequences some transcription takes place & histones can also get lost
What is the role of macro-H2A and transcriptional expression?
- Macro-H2A (mH2A) is enriched at inactive X-chromosome
- C-terminal associates with histone deacetylases (HDACs)
- blocks nucleosome remodeling
- font-sizefont-familyActs as tumor suppressor t font-sizefont-familyin cancer
What is the function of H2A.B?
- Enriched at active X chromosome
- Results in less stable nucleosomes that are more accessible to transcription factors & RNA pol II
- Enriched at TSSs of actively transcribed genes & appears to facilitate transcription & play role in mRNA splicing
What are the function of H2A.X?
- The phosphorylated H2A.X is replaced after DNA repair by non-phosphorylated H2A.X
The question on the page originate from the summary of the following study material:
- A unique study and practice tool
- Never study anything twice again
- Get the grades you hope for
- 100% sure, 100% understanding
