2.1.2 Protein Ladder (Marker)

Protein Standards (Marker)
Protein standards (marker) are molecular weight reference substances placed next to sample proteins, which help estimate the size of the target protein after separation. Currently, there are mainly two types of standards available on the market: non-prestained markers and prestained markers.

Non-prestained protein markers: Their bands can only be visualized after electrophoresis is completed, followed by staining and destaining together with the target protein. They cannot be used to monitor the electrophoresis process or the membrane transfer effect in real time, which is inconvenient during experiments. However, they have an advantage: without dyes, their migration rate is similar to that of proteins, making them more accurate than prestained markers in indicating molecular weight.
Prestained markers: They allow real-time monitoring of protein separation on the gel during electrophoresis and the subsequent transfer effect onto the membrane.
2. Classification of Protein Markers
Category of Marker Specific Types
Non-prestained protein markers Wide-molecular-weight, high-molecular-weight, low-molecular-weight, ultra-low-molecular-weight protein markers
Prestained protein markers Single-color prestained, multi-color prestained protein markers
Chemiluminescent protein markers (Exposure markers) Non-prestained, prestained chemiluminescent protein markers