Question

Which of the following is incorrect about Purification of protein complexes followed by mass spectrometry?

(a) Isolating protein complexes from cells allows identification of interactions between ensembles of proteins instead of just pairs

(b) Systematic purification of complexes on a large scale is done by tagging hundreds of genes with an epitope

(c) UnLike in the yeast-two-hybrid assay, this does not involve chimeric genes

(d) Affinity purification based on the epitope will then extract all the proteins attached to the bait protein from cell lysates

I had been asked this question by my college professor while I was bunking the class.

My question is from Protein topic in portion Global Approaches for Studying Protein – Protein Interactions of Bioinformatics

Answer 1

Right option is (c) UnLike in the yeast-two-hybrid assay, this does not involve chimeric genes

Explanation: Like in the yeast-two-hybrid assay, this is done by making chimeric genes that are introduced into cells. The principle of mass spectrometric identification of proteins is that the protein is chopped into fragments by tryptic digestion, and the mass of each fragment is measured by matrix-assisted laser desorption/ ionization-time-of-flight mass spectrometry (MALDI-TOF MS). This measurement is so accurate that the combination of amino acids in each fragment can be calculated and compared to a database of all the proteins in the proteome of the organism in order to find the correct one.