Cell Communication Wins Chemistry Nobel

Americans Robert J. Lefkowitz and Brian K. Kobilka won the 2012 Nobel Prize in Chemistry this morning for research that helped to reveal how cells communicate.

Semi-permeable cell membranes are one of the most astounding features of life, allowing many cells to coordinate into organs, organ systems and organisms. Cell membranes at once protect the fragile contents of each cell and maintain contact with other, sending and receiving signals and communicating across barriers. Otherwise there could be no taste, smell, muscle contraction, or virtually any other action.

But for much of the history of biology this communication remained mysterious. For instance, consider the example of adrenaline. A rush of it focuses your attention and quickens your heartbeat, but adrenaline itself never enters your cells.

Lefkowitz and Kobilka discovered a key mechanism for transmitting information from the outside of a cell to the inside without actually bringing any external material in through the barrier. They found G protein-coupled receptors (GPCR) embedded in cell membranes, which, through a three-part system, allow the cell to sense changes in the external environment.

GPCR receptors are embedded in the two-layer membrane always, waiting to be contacted by their specific outside trigger particle, or ligand. This be something like a hormones or neurotransmitter. When the receptor locks on to its ligand on the outside, the receptor changes shape. This opens up a keyhole perfectly shaped for a G protein, otherwise floating freely within the cell, to bind to the inside of the receptor. When the G protein joins to the receptor, the group changes shape again, setting off a cascade of signaling changes within the cell.

Lefkwitz proposed this general mechanism for signaling across membranes, called the ternary complex model, in 1980. Kobilka discovered the three dimensional structure of one of the actual proteins in 2011. Nearly half of all medications act by triggering G protein-coupled receptors.

Source: http://www.popularmechanics.com/how-to/blog/cell-communication-wins-chemistry-nobel-13574896?src=rss

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