We have developed a method for the immunoaffinity purification of calnexin, an endoplasmic reticulum molecular chaperone, and analyzed the molecular weight of purified calnexin using matrix-assisted laser adsorption ionization time of flight mass spectrometry (MALDI TOF-MS). Calnexin was thereby found to have a molecular weight of 66.1×103, which is nearly identical to the molecular weight estimated from the protein sequence.
