What can I use as a positive control or marker on my western blots?
The Positope control protein (Cat. No. R90050) is designed to be used as a positive control in western blotting for a variety of antibodies. The control protein is a 53 kDa highly purified recombinant protein that contains seven epitope tags including the Xpress, c-myc, V5, His(C-term), HisG(N-term), Thioredoxin, and GFP.
The MagicMark XP Western Protein Standard (Cat. No. LC5602) consists of peptides that contain an IgG binding domain. These peptides can be detected with your regular antibodies and provide a way for you to get good molecular weight estimations without having to rely on transferred pre-stained standards.
What is the composition of the MagicMark XP Western Protein Standard?
MagicMark XP standards consist of a mixture of eight E. coli-expressed recombinant proteins ranging in size from 20 to 120 kDa. Each protein contains an IgG binding sequence from Protein G. This IgG binding site binds the primary or secondary antibody used to detect your target protein, allowing you to detect the MagicMark standard directly.
I used your MagicMark XP Western Protein Standard and obtained a very weak or almost no signal after the western detection. Can you please help me troubleshoot?
Here are some suggestions:
- Verify that the detection reagents are working well. Optimize the antibody concentration to obtain best results.
- Make sure that the amount of standard loaded on the gel is correct.
- Optimize the transfer conditions (current, voltage, transfer time).
- Enzyme-conjugated primary antibodies may not bind efficiently with the proteins in the MagicMark XP Western Protein Standard. We recommend using unconjugated primary antibody, followed by the addition of enzyme-conjugated secondary antibody.
Note: The Anti-myc-AP/HRP and Anti-V5-AP/HRP antibodies do not bind to MagicMark XP proteins.