Proteomics
STUDENT ACTIVITY
One regulatory protein implicated in causing cancer is p53. Go to the NCBI Web site and
look up the protein sequence of human p53 (accession number AF307851) and mouse
p53 (accession number X00741).
The NCBI Web site link is:
http://www.ncbi.nlm.nih.gov/
Then use the protein analysis toolkit (ExPASy proteomics toolkit page) to analyze these
two p53 proteins.
The ExPASy proteomics toolkit Web site link is:
http://us.expasy.org/tools/
Using the two Web sites, answer the following questions:
1. What kind of tools are available? List 5 different kinds and a brief
description of what each type does.
2. Use the ProtParam tool for both protein sequences. How many amino
acids does each protein have? What is the theoretical molecular
weight for each protein?
3. Use the Prosite tool for one of the proteins. What post-translational
modifications are possible on p53? Are these all actually found on
the protein inside the human or mouse?
4. Do a sequence alignment of the two proteins using the SIM
alignment tool. What do the * symbols mean below the aligned amino
acids? What is the percent identity? What does that mean?
Hint: Begin your analysis using the Proteomics toolkit tools by cutting and pasting the
p53 protein sequences from the NCBI gene listing. Be careful to copy the protein
sequence and not the DNA sequence.