David's theory of evolution: God's error corrections IV (Evolution)

by David Turell @, Wednesday, October 21, 2020, 21:10 (39 days ago) @ David Turell

Tight controls of cell division:

https://phys.org/news/2020-10-cell-division.html

"During cell division specific target proteins have to be turned over in a precisely regulated manner. To this end specialized enzymes label the target proteins with signaling molecules. However, the enzymes involved in this process can also label themselves, thus initiating their own degradation. In a multidisciplinary approach, researchers identified a mechanism of how enzymes can protect themselves from such self-destruction and maintain sufficient concentrations in the cell.

"Vital functions of multicellular organisms, such as growth, development, and tissue regeneration, depend on the precisely controlled division of cells. A failure in the underlying control mechanisms can lead to cancer.

***

"A critical step in cell division is the distribution of genetic information evenly between daughter cells. This process is controlled by a large protein complex, the anaphase-promoting complex/cyclosome (APC/C), which labels proteins with a signaling molecule known as 'ubiquitin.' The ubiquitin label functions essentially as a molecular postal code, targeting labeled proteins to the cellular protein degradation machinery. To allow for efficient and precise labeling of target proteins, the APC/C works together with an ubiquitin-conjugating enzyme, UBE2S. However, UBE2S also has the ability to modify itself with ubiquitin, thus initiating its own degradation. This ability applies to ubiquitination enzymes in general. "This raises the fundamental question of how ubiquitination enzymes find the right balance between labeling their targets and labeling themselves to ensure that sufficient quantities of the enzymes are available in the cell," says Sonja Lorenz.

"The new study provides an answer to this question by showing that UBE2S can adopt an inactive state in which it is unable to label itself with ubiquitin. "When UBE2S forms a dimer, i.e., two molecules pair with each other, they become inactive and protected from self-destruction," says Jörg Mansfeld. The scientists suggest that this mechanism ensures that a stable cellular pool of UBE2S is preserved and re-activated when required. The cell can thus control the ratio of active and inactive UBE2S to fine tune cell division."

Comment: I've discussed the requirement for reactions at high speed. Mitosis is constant and also at high speed. This study shows the complexity of mistake controls designed by God.


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