Extracellular Juxtamembrane Segment of ADAM17 Interacts with Membranes and Is Essential for Its Shedding Activity

A wide variety of biological processes including differentiation, regeneration, and cancer progression are regulated by shedding of membrane-anchored proteins. One of the major sheddases is A Disintegrin And Metalloprotease-17 (ADAM17) whose extracellular region consists of a pro-, a catalytic, a disintegrin-, and a membrane-proximal domain (MPD) as well as a short juxtamembrane segment of 17 amino acid residues that has been named Conserved ADAM-seventeeN Dynamic Interaction Sequence (CANDIS). This segment is involved in substrate recognition. Key mediators of inflammation including interleukin-6 receptor (IL-6R) and tumor necrosis factor (TNF-alpha) are substrates of ADAM17. The shedding activity of ADAM17 is regulated by the conformation of the membrane-proximal domain preceding the CANDIS segment. Here, we show that CANDIS, besides being involved in substrate recognition, is able to interact with lipid bilayers in vitro and that this property could be involved in regulating ADAM17 shedding activity.