Localization of ETR1(1-147)-TAP to the endoplasmic reticulum based on analysis by sucrose density gradient centrifugation.

Arabidopsis membranes were fractionated over 20–50% (w/w) sucrose gradients. Gradients were run in the presence of Mg (+) to stabilize membrane-associated proteins or in the absence of Mg (−) to dissociate membrane-associated proteins. Samples (20 µL) of each fraction were analyzed by immunoblot for ETR1(1-147)-TAP, the ER marker ACA2, the PM marker H⁺-ATPase, the mitochondrial inner membrane marker F1-ATPase (pM021), the Golgi marker α-mannosidase, and the vacuole marker VM23.