Page 94 - The Miracle in the Cell Membrane

The Miracle in the Cell Membrane

cells for exam ple can dis tin guish the body's own cells
from for eign bod ies like virus es and bac te ria. Cells such
as the T-cells in the immune sys tem use rec og ni tion pro -
teins to tell wheth er any par tic u lar cell belongs to the
body or not. Since sur gi cal ly trans plant ed tis sue pos sess -
es the wrong rec og ni tion pro teins, the immune sys tem
rejects such organs unless it is sup pressed. These same
pro teins also per mit the sperm cells to recog nize the egg
cell.
The rec og ni tion pro teins in the cell mem brane are the
tar get of virus es and bac te ria, because tox ins bind to rec -
og ni tion pro teins in order to kill cells. Under typical con -
di tions, as a result of these pro teins, the con nec tions
between cells reg u late cell growth. But in a can cer cell,
for exam ple, the num ber of rec og ni tion pro teins is very
low. For that rea son, the immune sys tem can not iden ti fy
the can cer cells that need to be elim i nat ed. 33

Channel Proteins

Some proteins form channels along the length of the
cell membrane. These proteins have two special sections:
the fat-friendly part that adheres to material in the cell
membrane, and the water-friendly part that forms in the
inner part of the channel. In this way, a route is formed
for water-soluble substances to move in and out of the
cell. These proteins, function like gates and regulate the
movement of molecules entering and leaving the cell,

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