evolution: pressure-sensing proteins (Introduction)

by David Turell , Wednesday, August 21, 2019, 23:49 (1919 days ago) @ David Turell

Absolutely necessary for complex organisms who need to feel bowel and bladder pressure, control of blood pressure, touch, etc. Specialized complex proteins must b e developed and employed:

https://phys.org/news/2019-08-scientists-basics-pressure-sensing-piezo-proteins.html

"A team of scientists from Weill Cornell Medicine and The Rockefeller University has illuminated the basic mechanism of Piezo proteins, which function as sensors in the body for mechanical stimuli such as touch, bladder fullness, and blood pressure.

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"They confirmed this complex protein's structure and showed essentially how it can convert mechanical stimuli into an electrical signal.

"'Our analysis shows that tension on the cell membrane in which Piezo1 is embedded can flatten and widen the protein's structure," said co-senior author Dr. Simon Scheuring,

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"Piezo1 and Piezo2 are very large and complex proteins with unique structures. They are embedded within the membranes of certain cell types, and their function is to transduce mechanical force on cells into electrical signals that alter cell activity. Piezo1 proteins work for example in bladder cells to detect when the bladder is full, and in blood vessel-lining cells to detect and help regulate changes in blood pressure. Piezo2 proteins work in sensory nerve endings in the skin and joints, helping to mediate the senses of touch, pain, and proprioception—the sense of how one's limbs are arranged.

"Advances in imaging techniques have enabled scientists in recent years to determine the basic structure of Piezo1—a structure that Piezo2 is thought to mostly share. From above this structure has a three-armed, propeller or "triskelion" appearance. (my bold)

"From the side it looks like a shallow bowl embedded in the cell membrane, with an ion channel at its center. The latter, when opened, allows a flow of calcium and other positively charged ions into the cell.

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"They showed with these methods that Piezo1 is a springy structure that normally bends the cell membrane where it sits, but will flatten out when, for example, a mechanical force is applied to the cell membrane.

"'As the membrane tension increases, the structure of Piezo1 flattens and stretches out to occupy a larger area, which in turn opens the ion channel," Dr. Scheuring said.

"He noted the possibility that other stimuli that stretch and flatten the Piezo1 structure, such as a pulling force on its arms from the inside or on an external domain called the CED from the outside the cell, in principle could open the ion channel—making it a suitably versatile mechanism for the wide range of cell types and physiological functions in which it works."

Comment: This three-armed propeller-like shape is an extremely specialized construction. It absolutely has to have been designed. Chance would never discover this form and its electrical functionality. Bipedal walking would be impossible without proprioceptive sensors placed throughout the body. Not by Darwin.