Final answer:
In a two-dimensional gel electrophoresis experiment, proteins are generally separated vertically by their isoelectric point (pI), which is the pH at which a protein has no net charge.
Step-by-step explanation:
In a two-dimensional gel electrophoresis experiment, proteins are generally separated vertically by Isoelectric point (pI), which is the pH at which a protein has no net charge. Two-dimensional gel electrophoresis combines the separation of proteins based on their pI and molecular mass to achieve greater resolution.