Genome complexity: cell control of gene expression (Introduction)

by David Turell , Sunday, September 22, 2019, 18:51 (1668 days ago) @ David Turell
edited by David Turell, Sunday, September 22, 2019, 19:05

A protein complex in cells directs gene expression:

https://phys.org/news/2019-09-insight-cells-identity.html

"All of the more than 200 different cell types in our body contain the same DNA. Which of those genes that are expressed determine each cell type. Therefore, it is essential that the activity of the genes is controlled with great precision.

"Thus, a stem cell may develop into anything from a skin to a bone cell, depending on which parts of the genome are expressed.

***

"One of the key protein complexes that regulates whether genes are turned on or off is called PRC2. To ensure that the complex binds to the right places in the genome, a number of other proteins are associated to PRC2.

"In the recently published article, the research group has studied the importance of six different proteins associated with PRC2, and the group has shown that all six proteins help direct PRC2 to the right places in the genome.

"In 15 different combinations, the researchers removed the associated proteins from embryonic stem cells one by one. In this way, the researchers were able to study the contribution of each protein to the activity and binding of the PRC2 complex to specific areas. It was found that the ability to find the way to the right places in the genome remained intact until all six associated proteins were removed from the stem cells.

"That finding surprised the researchers, says the study's lead author, Postdoc Jonas Højfeldt:

"We assumed that each of the associated proteins was responsible for its own area to where the PRC2 complex should be guided. Instead, we saw that they all contributed to the places where the complex binds. As long as just one of the associated proteins were left, the ability remained intact," he says."

comment: The importance of activating the correct genes in each cell is backed up by a complex of six special proteins each of which can do the job. Such a system has to be designed, and cannot develop by chance. How does a mindless mechanism recognize the need for such an important backup system?