The following is a list of mutations that have been in a gene that has more than
ID: 35072 • Letter: T
Question
The following is a list of mutations that have been in a gene that has more than 60 exons and encodes a very large protein of 2532 amino acids. Indicate whether or not each mutation could cause a detectable change in the size or the amount of mRNA and/or a detectable change in the size or the amount of the protein product. (Detectable changes in size or amount must be greater than 1% of normal values.) What kind of change would you predict?
a) Lys576Val (changes amino acid 576 from lysine into valine)
b) Lys576Arg
c) AAG576AAA (changes codon 576 from AAG to AAA)
d) AAG576UAG
e) MetlArg (there are at least two possible scenarios for this mutation)
f) promoter mutation
g) one base-pair insertion into oodon 1841
h) deletion of codon 779
i) IVS18DS, G-A, + 1 (this mutation changes the first nucleotide in the eighteenth intron of the gene, causing exon 18 to be spliced to exon 20, thus skipping exon 19).
j) deletion of the poly-A addition site
k) G-to-A substitution in the 5'UTR
l) Insertion of 1000 base pairs into the sixth intron (this particular insertion does not alter splicing)
Circle Y for yes or N for no in the first two columns. Enter
Explanation / Answer
a) Lys576Val (missence mutation): No change in the mRNA as well as Protein size or level expected, but the strucure and function of the protein might be altered because of the change in positively charged aminoacid (Lys) to nonpolar uncharged aminoacid (Val).
b) Lys576Arg (Neutral mutation): No change in the mRNA as well as Protein size or levels expected.
c) AAG576AAA (Silent mutation): No change in the mRNA, Protein size or levels expected. (Both AAG, AAA code for Lys aminoacid).
d) AAG576UAG (Nonsense mutation) : No change in the mRNA length as well as levels expected. This change may not affect the protein levels, however, it certainly results in the truncated protein (shorter in size than the original or wild type protein).
e) MetlArg (Missense mutation)(there are at least two possible scenarios for this mutation): If it is a start codon change from Met to Arg, there may not be change in the length and levels of mRNA however this mRNA certianly would not code for any protein.
f) promoter mutation (None): Mutation in the promoter results leads to no mRNA and no protein production as well
g) one base-pair insertion into codon 1841 (frameshift mutation): One base insertion into codon 1841 results in frameshift mutation may not affect the length or levels of RNA however it might certainly brings the changes in the size of the protein because of the frameshift. However, Protein levels may not change.
h) deletion of codon 779 (none): Deletion of codon 779 certainly would change the length of RNA by 3 nucleotides but the levels of mRNA would remain unchaged. This deletion may not change the protein levels but would definitely change the size of the protein by one aminoacid. (the change in mRNA length and proteins size would be less than 1%)
i) IVS18DS, G-A, + 1 (this mutation changes the first nucleotide in the eighteenth intron of the gene, causing exon 18 to be spliced to exon 20, thus skipping exon 19)(None): This change might not resulst in the levels of mRNA, however it alters the length of mRNA as well of the size of protein but not the levels of protein.
j) deletion of the poly-A addition site (None): It may or may not change the mRNA levels. However, this change would certainly alter the length of the mRNA. Since poly-A tail is important in protein translation the protein may not expressed.
k) G-to-A substitution in the 5'UTR (None): No change in the length as well as the levels of mRNA expected. Though this change may not affect the protein size, it might alter the protein levels if this is an important mutation (if it is a trnaslation enhancer).
l) Insertion of 1000 base pairs into the sixth intron (this particular insertion does not alter splicing)(None) : No change in the levels or length of mRNA as well as protein.
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