Why does EGR1 run at 75kDa on a western blot when its predicted size is 58kDa?

Even though EGR1 has a predicted size of ~58kDa, 75kDa is the correct running size. This is because EGR1 is Sumoylated, which along with other PTMs, increases the size it runs at on a western blot. 

Last updated: August 3, 2025