Immunity system complexity: how T cells are triggered (Introduction)

by David Turell @, Monday, April 01, 2019, 20:04 (198 days ago) @ David Turell

The surface detectors and the triggering mechanism are now known:

https://phys.org/news/2019-04-breakthrough-cell-immune.html

"For the first time ever, scientists have imaged the process by which an individual immune system molecule is switched on in response to a signal from the environment, leading to the critical discovery that the activation process involves hundreds of proteins suddenly coming together to form a linked network through a process known as a phase transition.

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""This is something that happens inside a living cell during the process of the cell making a decision—signal transduction is what we call it—and it's how cells 'think' with chemical reactions," said study leader Jay Groves, (my bold)

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"The team's revelation came about as part of the ongoing research by the Groves lab on the physical mechanisms of T cell signaling and the Ras protein. Found in all eukaryotic cells in multiple variations, Ras wears many hats, including acting as a regulator for cell growth, division, and death. T cells, the immune system cells that detect foreign and potentially harmful infections, use Ras as an on-off switch for the intruder alert pathway that launches a protective response. The T cell's ability to distinguish a real external signal—when a foreign molecule binds with the aptly named T-cell receptor (TCR) on the cell surface—from inadvertent contact with nearby proteins is critical for a functioning immune system. If a T cell accidentally reacts to one of our own molecules, then an autoimmune disease can develop. At the same time, if a T cell loses its sensitivity, then viruses will be able to grow unchecked and cancerous cells won't get cleared from the body.

"Due to the wide implications for human health, scientists have long wondered how the cells regulate their signals in order to achieve this balance. Past research had revealed that a T cell's Ras proteins don't interact directly with cell receptors. Instead, receptors send the "on" signal to internal intermediary proteins, including a key group of three proteins, known as LAT, Grb2, and SOS, that ultimately pass the signal to Ras.

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"In the current study, the scientists used microscopy to watch the moment that a T cell receptor on a supported membrane microarray asked a single SOS molecule to activate. Instead of responding right away, SOS waited for 10 to 30 seconds before turning into its active state. If the nearby LAT and Grb2 molecules underwent the phase transition with SOS, and condensed into their assembled state, they could hold SOS on the membrane long enough for SOS to activate. Without the phase transition, the long delay in the SOS molecule would prevent it from activating before it left the receptor.

"'It's like the protein has a delay built into it," explained Groves. "It needs the phase transition combined with sustained signaling, and only then will it turn on.'"

Comment. Note the bold. The direct implication by the quoted scientist, is that cells 'think' with automatic molecular reactions that cause the proper necessary result, my point all along in these discussions. Since infections are a constant threat to life, living organisms could not have been brought into existence unless these immune mechanism were present from the beginning, by design. Please look at the complexity of the molecules structure shown on the website, which also makes as strong case for design. Cells do not think, but automatically react swiftly to all stimuli by their designed reactions of complex organic molecules.


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