Fig. 2.

A generic diagram of a force-bearing focus in animals. (A) Representation of the components of such a focal ensemble with protein a, which has an extracellular domain that anchors outward. It makes a single pass per protein through the membrane and binds protein b, which then binds other proteins, including those (c) that recruit cholesterol and those (e) that bind the cytoskeleton (f) as well as enzymes (g) or channels (h). In type 1, the cell–cell junctions, a is cadherin, b is catenin, c is an SPFH-domain protein such as stomatin, and e can be vinculin that binds F-actin (f). In type 2, the cell-matrix junctions, a is the αβ integrin dimer, b includes talin, c is an SPFH protein such as flotillin, and e includes α-actinin and filamin that binds F-actin (f). The SPFH proteins gather cholesterol to produc-the ordered lipid platform (yellow) distinct from the disordered lipid membrane (blue). The entire ensemble bears a constitutive ∼picoNewton stretch (red arrow) at rest. Not drawn to scale. (B) Representation of such a focus at its constitutive state (Upper) and under added tension (Lower). The tension on the tether (upward arrow) is redirected into membrane stretch (two-headed arrows) by and confined within the ordered lipid platform (yellow).