Isolation of the Plasma Membrane: Membrane Markers and General Principles

This chapter discusses three techniques for the isolation of plasma membrane-enriched fractions from the plant tissue. The first technique is developed for the preparation of plasma membrane fractions from young, nongreen tissues, and the second technique is developed for the use with storage tissues where it is particularly useful for the production of plasma membrane fractions in bulk quantities. The third procedure utilizes aqueous polymer partitioning and has broad application, but is particularly well suited for situations where it is desirable to obtain vesicles with a uniform sidedness or for the use with leaf tissues where contamination by chloroplast membranes can be a problem. In addition to methods for the isolation of plasma membrane fractions, protocols are also described for the membrane markers most frequently used during plant membrane isolations. To identify the plasma membrane and assess contamination by other membrane components during a membrane isolation procedure, specific markers are required.