Protein Molecular Weight Markers
Pre-stained and labeled molecular weight marker mixes (protein MW markers) for protein electrophoresis (SDS-PAGE) to facilitate detection and assessment of relative protein sizes in colorimetric, fluorescent and chemiluminescent methods.
Protein MW markers or protein ladders are mixtures of proteins of known molecular weight (MW) or molecular mass (kDa) that are used to assess the relative molecular sizes of proteins that have been separated by electrophoresis. Typically, molecular weight markers are run in the outer lanes of a gel for comparison to test samples that are run in the middle lanes.
A standard curve can be constructed from the distances migrated by each marker protein. Then the distance migrated by the sample proteins can be plotted and their molecular weights calculated by interpolation. More often, however, MW markers are used as a reference to help confirm the identity of proteins of interest whose sizes are already known.