Anthrax toxin receptor 2 (ATR2), also designated capillary morphogenesis gene 2 (CMG2), is a cellular receptor for anthrax toxin. ATR2/CMG2 is a type 1 membrane protein that includes an extracellular von Willebrand factor A (VWA) domain with a metal ion-dependent adhesion site (MIDAS) motif. ATR2/CMG2 binds to protective antigen (PA) which is one of the three monomeric proteins which are released as anthrax toxin from Bacillus anthracis. Once bound, PA facilitates the delivery of the other two proteins, edema factor (EF) and lethal factor (LF), into the cytosol. Mutations in the gene ATR2/CMG2 result in inhibition of binding by the vWA domain, associated with infantile systemic hyalinosis (ISH) and juvenile hyaline fibromatosis (JHF). ISH and JHF are rare stiff-skin syndromes characterized by hyaline desposition in various organs, especially the skin and gingiva.