Brush border cytoskeleton and integration of cellular functions

The primary function of the intestinal epithelial cell is the absorption and transport of nutrients and electrolytes from the lumen of the gut to the organism's blood supply. The absorptive membrane on the lumenal surface ofthe cell-the brush border-has been the subject ofintensive physiological and chemical study . Similarly, the exquisite array of actin filments and associated binding proteins that underlies this membrane is among the best-characterized actin-based cytoskeletal structures in nature . Consequently, one would think that the brush border is a system uniquely suited for the study of the cytoplasmic matrix and the integration of cellular functions. Future studies may prove this to be true, but at present, almost nothing is known about how the cytoskeletal apparatus of the brush border participates in absorption, or any other cellular function of the intestinal epithelial cell . Nevertheless, this subject invites speculation. We first will give an overview of the brush border cytoskeleton and then summarize results of several in vitro experiments that have provided a basis for speculation on the function ofthe brush border cytoskeleton in vivo .