Figure 5

Schematic representation of the proposed hypothesis. Shown here is TGFβ1 pro-protein on the membrane. Inside (dashed line) is active TGFβ1 non-covalently bound to LAP and thus unable to bind to TGFβ1 receptors, which transduce signal. In the alcoholic lung, the expression of integrin αvβ6 is increased on epithelial cells, which binds to LAP on the alveolar macrophage. Because of the conformational change in the LAP, TGFβ1 slides out and is able to bind to the TGFβ1 receptors on the epithelial cells. This leads to decreased alveolar epithelial type II barrier function.