Biological complexity: nuclear pore architectural complexity (Introduction)

by David Turell , Thursday, March 15, 2018, 20:44 (2445 days ago) @ David Turell

The nucleus has a double membrane and complex pores to allows molecules in and out under tight control:

https://www.sciencedaily.com/releases/2018/03/180315130704.htm

"Like an island nation, the nucleus of a cell has a transportation problem. Evolution has enclosed it with a double membrane, the nuclear envelope, which protects DNA but also cuts it off from the rest of the cell. Nature's solution is a massive -- by molecular standards -- cylindrical configuration known as the nuclear pore complex, through which imports and exports travel, connecting the bulk of the cell with its headquarters.

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"The pore complex contains 552 component proteins, called nucleoporins, and scientists hadn't previously known how they all fit together. It took a combination of approaches to assemble a comprehensive map of these pieces.

"The pore complex first emerged when single-celled organisms -- the only living things at the time -- acquired special compartments containing organ-like structures, including the nucleus, which houses the cell's genetic code.

"It serves not only as a conduit to and from the nucleus, but also as a checkpoint regulating what passes in and out. Genetic instructions transcribed into RNA are allowed to exit, for example, while proteins needed inside the nucleus may enter. Other things, such as viruses bent on taking over the cell, are kept at bay.

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"They uncovered a complicated ringed structure containing rigid, diagonal columns and flexible connectors that evoke the towers and cables of human-made structures like the Golden Gate Bridge."

Comment: When the nucleus appeared, this control mechanism had to be in place. This means 552 proteins had to be found to construct this extraordinary structure all at once. It is designed, and not by chance.