Loading Control Antibodies

Popular loading controls used may be housekeeping gene proteins or other proteins that are expressed constitutively across all cell types. Loading controls are proteins that are highly conserved, highly expressed, and stable under most experimental conditions. Expression is rarely affected by biological or experimental variations.

• Experimental failures that may be introduced via human error (uneven quantity of protein added to well) can be almost immediately distinguished. This improves efficiency and reduces time of experiments as there is no time wasted dealing with inaccurate or inconclusive results.
  
  
• Loading controls are used to establish if there has been even transfer not only of the sample, but also of the gel across the membrane. This is another common issue associated with western blot.
  
  
• The use of a loading control can also correct for the ‘edge effect’. This is when proteins added to wells at the sides of the gel drift in towards the centre. Loading controls can establish and control for this.

Although under most conditions loading control proteins do not vary in expression there may be some exceptions. These include:

• Loading control proteins may vary in expression across different tissue types (higher beta actin expression in skeletal muscle vs. elsewhere in the body).
• Loading controls proteins may vary in expression in different disease states (e.g. cancer).
• Loading controls proteins may vary in expression depending on age of subject from which the sample was taken.
• The loading control of choice must have a different molecular weight than the protein of interest so that the researcher can distinguish between the bands when performing western blot.