Inverse (I)-BAR, also known as the IRSp53/MIM homology Domain (IMD), a dimerization module that binds and bends membranes
Inverse (I)-BAR (or IMD) is a member of the Bin/Amphiphysin/Rvs (BAR) domain family. It is a dimerization and lipid-binding module that bends membranes and induces membrane protrusions in the opposite direction compared to classical BAR and F-BAR domains, which produce membrane invaginations. IMD domains are found in Insulin Receptor tyrosine kinase Substrate p53 (IRSp53), Missing in Metastasis (MIM), and Brain-specific Angiogenesis Inhibitor 1-Associated Protein 2-like (BAIAP2L) proteins. These are multi-domain proteins that act as scaffolding proteins and transducers of a variety of signaling pathways that link membrane dynamics and the underlying actin cytoskeleton. Most members contain an N-terminal IMD, an SH3 domain, and a WASP homology 2 (WH2) actin-binding motif at the C-terminus, exccept for MIM which does not carry an SH3 domain. Some members contain additional domains and motifs. The IMD domain binds and bundles actin filaments, binds membranes and produces membrane protrusions, and interacts with the small GTPase Rac.