Coding, construction and placement of the CFTR protein.
Construction and placement of the CFTR protein in the cell membrane occurs in distinct phases. Located on the long (q) arm of chromosome 7 at position 31.2, the CFTR protein is comprised of 27 exons that encode its genetic sequence. An exon is a portion of a DNA that contains the code for a protein structure. The CFTR gene is transcribed into a single strand of RNA within the cell nucleus; regions that are not needed to make the protein are spliced out, producing the final messenger RNA (mRNA).
The mRNA is translated into protein by ribosomes after moving from the nucleus to the endoplasmic reticulum, or ER. A number of proteins called chaperones facilitate folding of the new CFTR protein and its transfer through the ER. CFTR is then further processed in the Golgi apparatus where sugars are added, and then sent to the apical surface of the cells.
