[26] Isolation of lumenal and contralumenal plasma membrane vesicles from kidney

This chapter focuses on the isolation of lumenal and contralumenal plasma membrane vesicles from kidney. This chapter is intended to provide some guidelines to isolate lumenal and contralumenal membrane fractions from renal epithelia. Experience has shown that the isolation of lumenal membranes is usually easier to achieve, probably because this cell membrane represents the cell pole that has undergone the highest degree of differentiation. Thus a separation of this membrane from the contralumenal membrane and from intracellular membranes can in most instances be accomplished based on the relatively simple principle of "differential precipitation”. There are problems with regard to the purity of the membrane fractions and with regard to their unambiguous assignment to a particular cell type and a particular cell surface. The extent to which these factors may interfere with experiments must be considered in every instance.