Thank you for your question. Western blotting membranes are microporous substrates to which proteins bind; the dimensions of the pore dictate the size of the protein that can successfully bind to the membrane without passing through. Membranes are available in two pore sizes. You have 0.45-µm pore membranes for most analytical blotting experiments, in which proteins have a molecular weight greater than 20 kD. Or there are the smaller 0.2-µm pore membranes, which are most suitable for low molecular weight proteins (less than 15 kD) that might move through larger pores. A good rule to follow: If detecting a protein loaded at low levels, or quantification is critical, choose the smaller size membrane.
Date published: 2019-02-14