concentrating protein lysates

[John A. Newitt]

If you are already pushing the protein loading limit of the SDS-PAGE
gel (e.g. greater than 100 micrograms per lane on your standard 
large-format gel, 0.75mm thick) and you still can't detect it with 
your antibody, there is little you can do besides enriching for your
protein antigen.  Alternatively, you could affinity-purify your 
primary Ab (provided you have pure, immobilized antigen with which 
to do this); this might allow you to increase the primary antibody 
concentration, and maybe the specific signal, without increasing the
background too much.

John  <newitt at ncifcrf.gov>