Protein extracts can degrade during prolonged storage at -20°C. A safer method of preservation is to complete the gel electrophoresis, followed by a protein transfer to a nitrocellulose or PVDF membrane, which is then air dried, protein side up (marked clearly for the future use). Membranes prepared in this way can be stored for up to 6 months in RT between sheets of Whatman, in a clean box. The benefits of this procedure include:
  • Additional unfolding of the proteins and fixing them into the membrane
  • Membrane will be ready to use any time for the next 6 months
  • Important samples can be processed promptly

Using this procedure, samples will be preserved and antibodies can be quickly validated using membranes prepared in advance. This will save precious time for the project. 

For proteins of low expression, like transcription factors, specific organs and cellular fractions have to be used to allow higher concentration of the target protein. Use this e-plant resource to check for expression levels and localization of a target protein in the species you are working with.

 Agrisera Standard Western blot protocol

Protein sample degradation during prolonged storage
Prolonged storage of protein samples can contribute to degradation of a target protein as shown for PsbB in samples stored for 2 years in -20°C.