ANKH

Progressive ankylosis protein homolog (ANK ilosis H omolog) is a protein that in humans is encoded by the "ANKH" gene.
This gene 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.