Comparative analysis of subcellular fractionation methods for revealing a-actinin 1 and a-actinin 4 in A431 cells

a-Actinin 1 and a-actinin 4 are actin-binding proteins with shared structural functions that are responsible for the regulation of several processes in the cell. Based on previous data on the different distribution of these proteins in the nucleus and cytoplasm, we have studied in detail the presence of a-actinin 1 and a-actinin 4 in subcellular fractions in the A431 cells spread on fibronectin. The detection of a-actinins in some particular fractions has been shown to depend on the method of lysis, as well as whether the preliminary low-temperature freezing of cells was used. The application of various fractionation methods has allowed us to conclude that a-actinin 4 is present in all cytoplasmic and nuclear subfractions, whereas, in addition to in the cytoplasm, a-actinin 1 can also be revealed in the nuclear envelope fraction.