Secreted phosphoprotein 2 (SPP2)

Secreted phosphoprotein 2 (SPP2), also referred to as secreted phosphoprotein 24 or SPP24, is a secreted extracellular matrix protein and a member of the cystatin superfamily, notable for its cystatin-like domain[1][2][4][5][11]. SPP2 is primarily involved in bone metabolism and is thought to coordinate aspects of bone turnover, likely due to its endopeptidase inhibitor activity, specifically inhibiting cysteine-type endopeptidases[1][4][11]. The gene is mapped to chromosome 2q37.1 in humans and encodes a protein of about 24 kDa, initially characterized as a minor component of cortical bone but broadly expressed in various tissues, especially in the liver[4][5][6]. SPP2 contains conserved disulfide-bonded loops typical of the cystatin superfamily and has been implicated in physiological and pathological processes such as retinitis pigmentosa (where certain mutations in SPP2 underlie autosomal dominant forms of the disorder) and hepatocellular carcinoma (as suggested by expression analyses)[2][9]. There is no evidence that SPP2 is a direct therapeutic target, as there are no known drugs that interact with or are designed to modulate SPP2, nor is it currently exploited as a clinical biomarker or associated with specific safety concerns in therapy[4][9][11].

Other names

Secreted phosphoprotein 24SPP24Spp-24SPP-24secreted phosphoprotein 24secreted phosphoprotein 224kDa24kD