Biological complexity: specific cell protein production (Introduction)

by David Turell , Monday, July 24, 2017, 19:03 (2679 days ago) @ David Turell

New techniques studying specific proteins show how complex cellular production actually is, and helps to differentiate subtypes of cells, not apparent when only microscopic studies are done:

https://www.quantamagazine.org/cell-atlases-reveal-biologys-frontiers-20170712/

"Analyzing patterns of gene expression in individual human immune system cells, the researchers refined the definitions of the types known as dendritic cells and monocytes and identified a novel type that had been overlooked. Moreover, they discovered that a cell population thought to comprise one subtype was actually a mixture of two, which perform different functions.

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"Turning their attention to the single-cell level, they mapped more than 12,000 proteins to 30 subcellular structures, in turn defining the proteomes — the complete sets of expressed proteins — of more than a dozen major organelles. The researchers identified which proteins were found where, explored variations in protein expression from cell to cell and analyzed how cells segregate chemical reactions within themselves.

"One of the paper’s most salient findings, according to its principal investigator, Emma Lundberg, was that as many as half of our proteins can be found in multiple compartments of a cell. “Everything that proteins do is specific within the context of their environment,” Lundberg said. “If one protein is present in the nucleus but also in the plasma membrane, it might have different functions in those compartments.”

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"As much as 50 percent of the proteins that her group observed were expressed in more than one part of a cell. If that figure indicates how big multi-functionality could be, Lundberg said, “it makes the cell much more complex and the functionality of the proteome greater.”
This heterogeneity offers deeper insights into the fundamentals of protein function, but it may also explain why, for instance, certain drugs result in unwanted side effects.

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"The team observed that approximately 15 percent of the proteins exhibited single-cell variation: In a tissue that looked superficially uniform, some cells might differ from their neighbors in the amount or spatial distribution of the proteins they expressed, when one would expect them to be the same. The single-cell RNA sequencing approach of the Human Cell Atlas will allow researchers to create cell profiles based on molecules other than proteins."

Comment: the point is that a cell might like exactly like another cell, but the two cells may be in different production modes, with different genes expressed. The finding of living complexity can only increase as new techniques are employed. Not by chance!