Biological complexity: make way for hemoglobin (Introduction)

by David Turell , Friday, August 18, 2017, 22:16 (2654 days ago) @ David Turell

Red blood cells are champion examples of design. They are shaped like donuts but the center is not completely open offering the best shaped surface diffusion area to allow oxygen to be delivered to the tissues and CO2 to be escorted out to the

https://medicalxpress.com/news/2017-08-hemoglobin.html

"Every cell in the body, whether skin or muscle or brain, starts out as a generic cell that acquires its unique characteristics after undergoing a process of specialization. Nowhere is this process more dramatic than it is in red blood cells.

"In order to make as much room as possible for the oxygen-carrying protein hemoglobin, pretty much everything else inside these precursor red blood cells—nucleus, mitochondria, ribosomes and more—gets purged. Jam-packing red blood cells with hemoglobin is essential. Doing so ensures that all the body's tissues and organs are well nourished with oxygen to carry on their normal functions.

"But how does this cell remodeling take place to begin with?

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"During cell specialization, unwanted parts of a generic, immature cell are removed by the proteasome, protein-gobbling strings of molecules, or the cells' "trash compactors," says study first author Anthony Tuan Nguyen, an HMS MD-PhD student.

"The researchers set out to find the mechanism that controls which parts get destroyed and which parts are spared before the precursor red blood cell becomes a full-fledged one.

"Finley had a hunch that the process was controlled by an enzyme called UBE2O, which he and colleagues identified in the 1990s. The enzyme marks cell parts for destruction by tagging them with a small protein called ubiquitin. This tagging allows the proteasome to recognize cells destined for destruction. The vast machinery, known as the ubiquitin-proteasome system (UPS), is switched on constantly throughout the body to remove unnecessary proteins and keep cells free of clutter.

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"While studying blood cells, Fleming had identified a mutant mouse that lacked the UBE2O enzyme. Knowing that Finley was interested in the enzyme and its possible role in cell specialization, Fleming contacted him.

"The researchers observed that mice without the enzyme were anemic, a marker of red blood cell deficiency. The observation supported the notion that UBE2O may play a role in red blood cell development.

"Using a series of tests that relied on large-scale protein analyses not available in earlier decades, the researchers confirmed the enzyme's role. Their results revealed that immature red blood cells lacking UBE2O retained hundreds of proteins and failed to become specialized.

"The researchers also demonstrated that when isolated from immature red blood cells and tested in other cell types, UBE2O still marked the right proteins for destruction, suggesting that the enzyme is the primary regulator of red blood cell specialization."

Comment: This is one of the best examples of design I've ever seen: the shape of the red cell, which is basically a bag of hemoglobin, hemoglobin, itself, with its unique properties of carrying oxygen in one direction and CO2 in the other, and its formation with the help a unique enzyme, remembering that all enzymes are huge molecules of a very specialized design. Only a planning mind can create this system.