1. Figure 1 Structure and composition of the brush border
Figure 1 | Structure and composition of the brush border. The brush border is composed of two interconnected regions, the microvillus assembly and the terminal web area. Structure and composition of the microvilli and the underlying terminal web are shown (1). Adhesion complexes are localted at the brush border, such as tight junctions, adherens junctions and desmosomes. Whether EpCAM is part of a precise adhesion complex is not currently known. Contractile forces are generated by the actomyosin network (black arrows) and actively contribute to brush border contraction and shape modulation. Microvillus clustering occurs via physical links provided by protocadherins (2). The 'treadmilling' phenomenon constitutes a dynamic equilibrium between actin polymerization at the tip of the microvillus (barbed end) and actin depolymerization at the actin rootlet (pointed end) (3). This process helps to maintain the microvillus at constant length, but also provides the required forces to push the plasma membrane and drive microvillus formation (black arrows). AJ, adherens junction; CDHR2, cadherin-related family member-2 (also known as protocadherin-24); EB-3, microtubule-associated protein RP/EB family member 3; EpCAM, epithelial cell adhesion molecule; MLPCDH, mucin-like protocadherin; TJ, tight junction.
Delacour, D. et al. (2016) Plasticity of the brush border — the yin and yang of intestinal homeostasis
Nat. Rev. Gastroenterol. Hepatol. doi: /nrgastro