The osteopetrosis associated transmembrane protein 1 (OSTM1) gene codes for the OSTM1 protein. OSTM1 protein is involved in osteoclast maturation and functional activity, more precisely, in cytoskeletal reorganization and development of the ruffled border of bone-resorbing osteoclasts. However, the exact function of the OSTM1 protein in osteoclastic bone resorption is still unclear. It has been identified that this protein acts as a G-alpha interacting protein and it has an E3 ubiquitin ligase activity which could regulate the protein activity through degradation via the ubiquitin-dependent proteasome pathway.
OSTM1 gene consists of six exons and spans approximately 33 kb on the long arm of chromosome 6 at 6q21. The OSTM1 protein consists of 334 amino acids weighing 37.2 KDa. This gene is normally expressed in normal fetal and adult osteoclasts and highly expressed in brain tissue. The mutations in this gene lead to the development of the most severe autosomal recessive form of osteopetrosis with central nervous system involvement.