Quantitative in situ gel electrophoretic assay for neomycin phosphotransferase activity in mammalian cell lysates

A method for the assay of neomycin phosphotransferase activity in eucaryotic cell lysates is described. Total cytoplasmic proteins are fractionated in nondenaturing polyacrylamide gels and then allowed to react in situ with [gamma-32P]ATP and kanamycin. The reaction products are detected by blotting to phosphocellulose paper and autoradiography. The assay is linear with protein concentration and sensitive enough to detect expression in transient assays.