The CTFR gene contains the sequence ---ATCATCTTTGGTGTT---, which codes for resid
ID: 1033619 • Letter: T
Question
The CTFR gene contains the sequence ---ATCATCTTTGGTGTT---, which codes for residues 506-510 of the protein.
A. Identify the residues in this segment of the protein.
B. In the most common mutated form of the gene, this same segment of DNA has the sequence ---ATCATTGGTGTT---
C. What type of mutation has occured and how does it affect the sequence of the encoded protein?
Cells have a mechanism for tagging and destroying proteins containing a C-terminal poly(Lys) sequence. What is the source of these proteins and why is destroying them helpful for this cell?
Explanation / Answer
Answer:
A):
The residues in this segment has the following sequence
Ile-Ile-Phe-Gly-Val
(B) & (C):
The mutation is the deletion of three nucleotides (CTT) which affects the codons 507 and 508. Thus, the resulting protein segment has the sequence Ile-Ile-Gly-Val, in which Phe 508 is missing. In other words, the mutation is a deletion mutation in which Phe (amino acid) is deleted.