Chromatography is frequently used to purify proteins from cellular extracts. There are various ...

A. The target protein can be covalently linked to the resin used to make the affinity column. When cell extracts are applied to the column, any proteins that associate with high affinity to your target will be bound until they are eluted in the presence of high-salt buffer.
B. You could instead use antibodies specific for your target protein. This is very similar to the first procedure, but instead of your protein being directly linked to the column resin, the antibodies are bound instead. The antibody will bind to your target, which should be bound to any associated proteins in the cell extracts.
C. One important limitation to recognize is that the antibodies could block the binding surface typically recognized by the other proteins that would normally bind to your target, reducing the number of binding partners isolated by the affinity chromatography. You would also need to have an antibody that recognizes your target protein that could be attached to the column in the first place.