Figure 2. MALDI mass spectrum of intact guinea pig AQP0

The urea-washed membrane pellets were delipidated by ethanol/acetone, and dissolved in 90% TFA. An aliquot (0.3 μL) was spotted onto the sample plate that was prelaid with DHB matrix. This spectrum shows that AQP0 molecular weight is approximately 28,260 Da, while the sample also contained a 20,000-Da protein and several minor proteins.