Site content for US residents only.
CF Source

CFTR:
The Protein Behind CF

CFTR proteins are made by cells to transport water and particles such as chloride ions into or out of cells. This helps maintain a healthy balance of water and salt in the body.

CFTR proteins are made when cells receive instructions from the CFTR gene to produce them. But the CFTR gene can have errors, or mutations.

The tabs below help explain how CFTR proteins work and how CFTR gene mutations produce defective CFTR proteins.

CF is the result of 2 disease-causing CFTR gene mutations that produce defective CFTR proteins. These proteins are too few in number, don't work right, or both.

Watch a video explaining how CFTR proteins are made and what happens when they do not work right.

CFTR proteins in a person without CF

In a person without CF, the cell produces CFTR proteins that work correctly. At the cell surface, the proteins act as channels between the inside and outside of the cells. These channels open and close to allow water and particles such as chloride ions to flow into or out of the cells. This helps the body maintain a healthy balance of salt and water.

CFTR proteins in a person without CF

CFTR proteins in a person with CF

In a person with CF, there are either too few CFTR proteins at the cell surface, CFTR proteins at the cell surface that don't work correctly, or both.

Too few CFTR proteins:
Too few CFTR proteins


CFTR proteins not working right:
CFTR proteins not working right

As a result, water and salt can't flow freely into or out of the cells like they should. This reduced water and salt flow can eventually lead to thick, sticky mucus building up in the lungs and other parts of the body, as well as other symptoms of CF.

Learn what causes defective CFTR proteins on the next tab

CFTR gene mutations affect CFTR proteins in 2 ways:

  • Mutations can affect how proteins function, or how well they do their job
  • Mutations can also affect the quantity, or how many proteins are at the cell surface

Some mutations can cause problems with both function and quantity at the same time.

Function of CFTR proteins

Some mutations can affect the ability of CFTR proteins to function.

Watch a video showing how certain CFTR mutations affect the way CFTR proteins function.

Quantity of CFTR proteins

Some mutations can affect the quantity of CFTR proteins at the cell surface.

Watch a video showing how certain CFTR mutations affect the quantity of CFTR proteins at the cell surface.

Click on any to see how different CFTR mutations can affect the FUNCTION or QUANTITY of CFTR proteins. Each of these defects is not necessarily found in all people with CF.

nucleus messenger RNA (mRNA) DNA chloride ions CFTR protein nucleus messenger RNA (mRNA) DNA chloride ions CFTR protein Affects quantity of proteins Because the channels are unstable, they are removed too quickly from the cell surface. There are too few channels at the cell surface. Affects quantity of proteins Proteins are not made correctly. The cell gets rid of them before they reach the cell surface. Affects quantity of proteins Instructions to produce the proteins are not always made correctly. Too few proteins make it to the cell surface. Affects quantity of proteins Instructions to make the proteins are not read correctly. No proteins are produced. Affects function of proteins Channels in the proteins at the cell surface are too narrow. Not enough chloride ions move into or out of the cell. Affects function of proteinsChannels in the proteins at the cell surface are not opening as often as they should. Not enough chloride ions move into or out of the cell. Affects quantity of proteins Because the channels are unstable, they are removed too quickly from the cell surface. There are too few channels at the cell surface. Affects quantity of proteins Proteins are not made correctly. The cell gets rid of them before they reach the cell surface. Affects quantity of proteins Instructions to produce the proteins are not always made correctly. Too few proteins make it to the cell surface. Affects quantity of proteins Instructions to make the proteins are not read correctly. No proteins are produced. Affects function of proteins Channels in the proteins at the cell surface are too narrow. Not enough chloride ions move into or out of the cell. Affects function of proteinsChannels in the proteins at the cell surface are not opening as often as they should. Not enough chloride ions move into or out of the cell.