Cell Signaling written by Michael

Search LMS site

Other LMS Site Pages: Basic Information First Steps Second Steps International Perspective General Approach to Treatment Treatment Techniques Treatment Choices by Site Coping with LMS Draft of Future Pages Links/Web Resources Glossary LMS Science Site Map Mirror Sites

Cell Signaling CellSignal Transport Growth Factor Ligands and Receptors Probable genetic causes of LMS How STI571 works for GIST with cKIT

Cell Signaling

Cells are in constant communication with one another. Cells communicate by sending and receiving signaling molecules called ligands. If ligands are the way that a cell speaks then cell surface receptors are the way that cells listen. If a ligand connects to the cells receptor then a message is conveyed to the cell. Different forms of communication depend on the ligand because a receptor can only take its particular form of ligand. The picture below represents a cell. Such a cell may have many types of receptors on its surface. In order to see these receptors we would have to get closer to the cells surface, until we can see the actual molecules that make up the cell.

This is what we might see if we could zoom in enough times to see cell surface receptors. As you can see the receptors have a section outside of the cell and a section within the cell. When a ligand binds to the receptor the message is sent into the cell. Ligands are shaped in order to fit exactly into a particular receptor. Different shaped receptors can only bind to the same shaped ligands.

Lets take the example of receptors that regulate cell growth. These are called the Tyrosine Kinase receptors and the ligands are referred to as growth factors. In our diagram we see two receptors that have not yet received a message. Sitting inside the cell is a chemical called RAS that is connected to GDP. When RAS is connected to GDP it is turned off and does not send the growth signal.

When the growth factors fit into the receptors the receptors connect together. This then causes P chemicals to connect to the receptors surface within the cell. A chemical reaction occurs in which SH2 connects to P, SH3 connects to SH2, SOS connects to SH3 causing GDP to be released from RAS and GTP to replace it. This is when the growth signal is sent to the neucleus. The GTP is then lost and replaced with GDP and the whole thing goes back to normal.

When RAS has mutated it takes on a different shape. This means that the GTP gets stuck within RAS and so the cell is permanently in the ON position constantly sending the signal to grow. Therefore once initially triggered, the cell will behave as if growth messages are constantly being received.

The information on this site is not a substitute for professional medical advice. You should not use this information to diagnose or treat a health problem or disease without consulting with your doctor. Please consult your doctor with any questions or concerns you may have regarding your condition. Copyright © 2001-2010 LMSWEBSITE