Methanol is normaly a good precipitant for proteins, like ethanol and
aceton too. However, this depends somewhat on the properties of the
protein, in particular its size and hydrophobicity.
The purpose of methanol in this procedure is more to make the membrane
permeable to small solutes than to fix the cells. You may have better
results by fixing first, for example with formaldehyde (4% in PBS) or
glutardialdehyde (1-2%) for single cells and Bouins solution for
tissue sections. By the way, the fear of formaldehyde in
immunocytochemistry is largely unfounded, only few monoclonal antibodies
do not react with aldehyde fixed tissues, polyclonals are almost always
ok.
