CFTR protein channel Flashcards
what type of protein is the CFTR protein
channel protein (requires ATP)
where in the body is the CFTR protein found
cell membrane of mucus producing cells (apical membrane)
lining of respiratory, digestive and reproductive systems
what is the roll of the CFTR protein
to transport Cl- ions across the cell membrane
how does a gene mutation in CF affect body systems (whole process)
gene mutation in CF gene changes the base sequence of the DNA
different mRNA codon will be coded for
different amino acid may be added to polypeptide chain (different primary structure)
stop codon can be in wrong place causing a shortened PP chain (no CFTR protein)
different amino acid sequence leads to different position of R groups
bonding may be different between groups in protein causing different tertiary structure (faulty CFTR protein)
faulty CFTR protein cannot transport Cl- ions out of cell into mucus
water cannot move into mucus by osmosis
mucus becomes thicker and stickier blocking the body systems
what does the CFTR protein do if there is an excess amount of water in the mucus
- Na+ is actively pumped across basal membrane
- Na+ diffuses through sodium channels in the apical membrane
- Cl- diffuses down electrical gradient
- water is drawn out of the cells by osmosis due to high salt concentration in the tissue fluid
5 water is drawn out of mucus by osmosis
what does the CFTR protein do if there is too little water in the mucus
- Cl- is pumped into the cell across the basal membrane
- Cl- diffuses through the open CFTR channels
- Na+ diffuses down the electrical gradient into the mucus
- higher salt concentration in the mucus draws water out of the cell by osmosis
- water is drawn into the cell by osmosis
what happens to the mucus of a person with CF
1.CFTR protein channel is non-functional/absent
2. Na+ channel is permanently open
3. water is continuously removed from the mucus by osmosis
4. mucus becomes thicker and stickier
