Biological complexity: how cells remove garbage (Introduction)

by David Turell , Saturday, November 07, 2020, 19:52 (1267 days ago) @ David Turell

Not fully understood but highly complex:

https://phys.org/news/2020-11-cell-dump-proteins.html

"In a new paper with results that senior author Eric Strieter at the University of Massachusetts Amherst calls "incredibly surprising," he and his chemistry lab group report that they have discovered how an enzyme known as UCH37 regulates a cell's waste management system.

"As he explains, a very large protease called a proteasome is responsible for degrading the vast majority of proteins in a cell; it may be made up of as many as 40 proteins. It has been known for more than 20 years that UCH37 is one of the regulatory enzymes that associates with the proteasome, he adds, "but no one understood what it was doing."

"It turns out that the crux of the whole process, he adds, is how complicated modifications in a small protein called ubiquitin can be. "In addition to modifying other proteins, ubiquitin modifies itself resulting in a wide array of chains. Some of these chains can have extensive branching. We found that UCH37 removes branchpoints from chains, allowing degradation to proceed.'" (my bold)

***

"This technique led to one more surprise. "Instead of acting as expected and opposing the degradation process, it turned out that UCH37 was removing branchpoints from ubiquitin chains to help degrade proteins," Strieter says. "You would think that by removing the signal for degradation that degradation would be impaired," he adds, "but it didn't work that way."

"In future experiments, Strieter and colleagues hope to further explore the degradation process and learn in more detail how UCH37 manages to regulate cellular function."

Comment: More evidence about how living protein molecules must work together perfectly at extremely high speed in nanoseconds or even shorter for life to function. This process involves very complex alteration of molecular sections. Note my bold