Someone ran an SDS-PAGE separation of a crude protein mixture product, and found a protein band at around 18,000 Dalton. It is suspected that this protein might be a mutant of a known protein. The mutant protein differs from the known protein by only the last two amino acids at the N-terminus of the peptide chain. Propose a most suitable method that can be used to determine whether this protein band is the known protein or the mutant protein. Must explain why you make this choice.

The dna in a cell’s nucleus encodes proteins that are eventually targeted to every membrane and compartment in the cell, as well as proteins that are targeted for secretion from the cell. for example, consider these two proteins: phosphofructokinase (pfk) is an enzyme that functions in the cytoplasm during glycolysis. insulin, a protein that regulates blood sugar levels, is secreted from specialized pancreatic cells. assume that you can track the cellular locations of these two proteins from the time that translation is complete until the proteins reach their final destinations. for each protein, identify its targeting pathway: the sequence of cellular locations in which the protein is found from when translation is complete until it reaches its final (functional) destination. (note that if an organelle is listed in a pathway, the location implied is inside the organelle, not in the membrane that surrounds the organelle.)