Optimization of western blotting for the detection of proteins of different molecular weight.

Protein samples electroblotted onto nitrocellulose membranes and quenched with a mixture of blocking agents produced a strong signal for cystic fibrosis transmembrane-conductance regulator (CFTR), a high-molecular-weight protein, in western blotting. Optimized conditions for CFTR were then extended to medium- and low-molecular-weight proteins (LAMP1 and Rab11a, respectively) to determine the effects of methanol concentration (0-20%) in Towbin's transfer buffer (TTB). Methanol in TTB appears to have little to no effect on CFTR signal.