PAGE-Mark™ 3-Color Series Protein Marker is ready-to-use protein marker which is pre-mixed for direct loading. Proteins are covalently coupled with a blue chromophore except for two reference bands (one green and one red band) when separated on SDS-PAGE (Tris-Glycine buffer). The PAGE-Mark™ 3-Color Series Marker is designed for monitoring protein separation during SDS-polyacrylamide gel electrophoresis, verification of Western transfer efficiency on membranes (PVDF, nylon, or nitrocellulose) and for approximating the size of proteins.