Band-Shift Analysis Using Crude Oocyte and Embryo Extracts from Xenopus laevis

The DNA-binding proteins play a pivotal role in the cell, regulating gene transcription, DNA replication and repair, it is therefore of fundamental importance that the mechanisms controlling these factors and their interactions be investigated. The study of DNA-binding proteins in the developing embryo would be extremely limited if one did not consider the use of the electrophoretic mobility shift assay, (EMSA also known as the gel retardation or band-shift assay) (1 ,2 ). Gel retardation is a fast, reliable and inexpensive assay, which can provide a wealth of information about DNA-binding proteins (3 –5 ). Band-shift analysis also provides an entry point to understanding the nature of DNA-protein interactions within the embryo.