Biological complexity:cells are factories with roadways (Introduction)

by David Turell , Wednesday, December 07, 2016, 01:32 (2909 days ago) @ David Turell

Cells are high speed protein producers with product carried along roadway within the cell and with guidance:

http://phys.org/news/2016-12-scientists-motors-maneuver-cells-roadways.html

"Cell motors travel an extensive network of roadways that are actually part of the physical structure, or cytoskeleton, which helps give our cells strength and shape, said Dr. Graydon B. Gonsalvez, cell biologist in the Department of Cellular Biology and Anatomy at the Medical College of Georgia at Augusta University.

"Microtubules and actin are the major roadways motors travel. The motors kinesin and dynein typically travel on microtubules; myosin is the motor running the actin roadway. To help make the math work with so few motors and so much cargo to move, there are adaptors that essentially help connect motor to cargo. The main adaptor for the kinesin motor is something called kinesin light chain; kinesin heavy chain is the motor part.

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"Gonsalvez is corresponding author of a study featured on the cover of the Journal of Cell Science that provides evidence of an adaptor running these roads that previously seemed to stay on actin.

"'It's switching parties, if you will," Gonsalvez said. "They are thought to not cross react. We found these systems have crosstalk."

"His research team used mass spectroscopy to analyze the proteins associated with the motor kinesin in the fruit fly. They looked specifically at oskar mRNA, a messenger RNA that makes proteins, which, in this case, help direct the orientation of the head and tail of a developing fruit fly embryo.

"They found among the protein crowd what appeared to be an outlier, a form of tropomyosin that they would have suspected would only show up as an adaptor for the actin roadway. "Here is a different kind of tropomyosin that is binding directly to a kinesin motor and functioning as the adaptor between this kinesin motor and the cargo," Gonsalvez said.

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"And, while motors do move proteins along with other cell inhabitants, it's more efficient to move the mRNA so the mRNA makes the protein right where it's needed, Gonsalvez said. The movement of motors seems to increase when they have a cargo, an apparent energy-conserving approach.

"Our 30,000 genes can make about 100,000 different proteins and are constantly at work. One of the many things that means is that a single gene can often make multiple different proteins. In a single cell at a single moment, there might be several thousand different proteins; and for each of those different proteins, there can be a hundred or more copies, Gonsalvez said.

"In a reinforcement of the concept that location is everything, misdirected mRNA and proteins can cause damage both because they aren't doing what's intended and because they likely are doing additional damage wherever they end up, Gonsalvez said.

"Gonsalvez likens the compartmentalization that occurs inside our cells to a house: Everything may be under the same roof, but very different things need to happen in the kitchen versus the bathroom."

Comment: Highly complex protein manufacturing factories with rope like roadways carrying product to the right spots, rarely an error. High complexity, not by chance!