Prestained protein ladders and unstained protein ladders (2024)

• Western blot protocol

Using a prestained protein ladder when running a western blot helps when you need to:
- monitor protein separation during SDS-polyacrylamide gel electrophoresis
- verify transfer efficiency between gel and membrane (PVDF, nylon, or nitrocellulose)
- calculate the approximate size of your protein by overlaying an image of the membrane with the ladder with the image generated by antibody staining.

Using an unstained protein ladderis very useful when you need to accurately calculate the size of your protein. However, an unstained protein ladder can only be visualized following staining with Coomassie or a similar non-specific protein stain. Unstained protein ladders are more accurate for sizing proteins, as the dyes used in prestained ladders can slightly distort the apparent size of the protein ladder proteins on the gel.

Protein ladders are most convenient to use when they are supplied ready to use, with no heating, dilution, or addition of reducing agent required before loading onto the gel. Prestained ladders also can use highlight bands of a different color, to make it easier to identify different size bands.

When choosing the right pre-stained protein ladder, the most important choice is based on the size of your protein of interest. For most researchers, we generally recommend:
a) ab116027 for proteins between 10 and 180 kDa
b) ab116028 for larger proteins up to 245 kDa
c) ab116029 for smaller proteins down to 3.5 kDa
d) ab116029 or ab234592 for studying smaller and larger proteins at the same time.

Table of prestained protein ladders

Chart showing sizes of individual protein markers in each prestained ladder