GRE Subject Test: Biochemistry, Cell, and Molecular Biology : Help with Post-Translational Protein Modification
Study concepts, example questions & explanations for GRE Subject Test: Biochemistry, Cell, and Molecular Biology
All GRE Subject Test: Biochemistry, Cell, and Molecular Biology Resources
Example Questions
Example Question #1 : Help With Post Translational Protein Modification
Which of the following is not an example of post-translational modification?
Myristoylation
Alkylation
Polyadenylation
Ubiquitination
Polyadenylation
Polyadenylation is an example of post-transcriptional modification. This process involves adding large repeats of adenine bases to the 3' end of mRNA molecules, known as the poly-A tail.
Myristoylation is the process of adding myristate (a fatty acid) to a protein, alkylation is the process of adding an alkyl group, and ubiquination is the process of adding a molecule of ubiquitin (a small protein often used to signal degradation).
Example Question #1 : Help With Post Translational Protein Modification
In which of the following organelles does the initial linkage of a sugar for post-translation modification N-linked glycosylation most commonly occur?
Golgi apparatus
Mitochondria
Nucleus
Endoplasmic reticulum
Endoplasmic reticulum
Two of the more common types of glycosylation, N-linked and O-linked, occur at different points and in different places in the cell. N-linked glycosylation takes place in the lumen of the endoplasmic reticulum, while O-linked glycosylation takes place in the Golgi body.
The other options, the mitochondria and the nucleus, are not involved in these post-translational modifications.
Example Question #2 : Help With Post Translational Protein Modification
Please complete the following statement:
"The addition of a CH3CO group to the N-terminus of a protein is the most common form of protein modification. This chemical modification is called ________."
Ubiquitination
Acetylation
Methylation
Phosphorylation
Adenylation
Acetylation
This question requires knowing either that CH3CO is an acetyl group, or that acetylation is the most common protein modification. Each of the other modifications described are biologically occurring modifications, but acetylation was the correct answer for the given statement.
All GRE Subject Test: Biochemistry, Cell, and Molecular Biology Resources
