Overview: [Characterization of red cell membrane proteins by SDS-PAGE] [research paper]
Topics: [gel analysis] [molecular mass standard curve] [measuring relative mobility] ["Hall of Shame"]
Data: [gel images]

Streaked Protein Gels Streaks – example 1 This one isn't so bad. The lane with the streaks (left of lane 5) is quite usable, in fact. The streaks came about because a portion of the more concentrated proteins in the membrane fraction precipated during the stacking process, then returned to solution after a fairly short time. Because of slight imperfections in the separating gel surface (it may have been allowed to dry a little before adding the stacking gel), the protein concentration was not uniform across the lane, and streaks rather than a uniform darker background are the result. The electric field was quite uniform, and diffusion minimal, otherwise the streaks would not remain as narrow vertical lines. Streaks – example 2 The fourth lane is streaked due to the effect described above. The electrical field was affected by the non-uniform concentration in the fourth lane (the dark one with streaks),, causing a narrowing of the bands. Note that the dye front was lost in this gel - it was allowed to run too long. Streaks – example 3 This one kind of stinks. Evidently, this group did not use an overlay after pouring the first gel layer. The result was a separating gel with the very rough top that you see here. As samples were stacked they were disproportionately concentrated in the 'valleys,' where the proteins precipitated. The precipitates re-dissolved gradually during the run, forming streaks instead of resolving into discrete bands.