Ankylosis, Progressive Homolog (ANKH)

ANKH encodes a multipass transmembrane protein that is expressed in joints and other tissues and controls pyrophosphate levels in cultured cells. Mutation at the mouse 'progressive ankylosis' (ank) locus causes a generalized, progressive form of arthritis accompanied by mineral deposition, formation of bony outgrowths, and joint destruction. The human homolog is virtually identical to the mouse protein and ANKH-mediated control of pyrophosphate levels has been suggested as a possible mechanism regulating tissue calcification and susceptibility to arthritis in higher animals.The human ANK gene is virtually identical to mouse ank, with only 9 amino acid differences over a 492-amino acid protein. There are 3 potential N-linked glycosylation sites and multiple putative phosphorylation sites.