Osteocalcin, also known as bone gamma-carboxyglutamate protein, is a vitamin K- and D-dependent, calcium-binding, non-collagenous protein. It has a molecular weight of approximately 5.9 kDa and contains 2–3 gamma-carboxyglutamate residues (Gla). Osteocalcin is produced only by osteoblasts and their dental counterpart, odontoblasts, and is an indicator of bone metabolism. The carboxylated form of osteocalcin is an indicator of bone formation, while its undercarboxylated counterpart is involved in glucose metabolism. Osteocalcin also acts as a hormone that regulates glucose and fat deposition as well as male fertility.
Alternate names: bone gamma-carboxyglutamic acid-containing protein, BGLAP.
ELISA Kits for Osteocalcin Detection
The Human Gla-Osteocalcin High Sensitive EIA Kit is designed to specifically differentiate human from bovine osteocalcin using a human osteocalcin-specific coated plate. This coated plate contains a monoclonal antibody that distinguishes human from bovine osteocalcin via their amino acid differences at positions 3 and 4 in the N-terminus. Using a human antigen-specific monoclonal antibody for capture greatly improves experimental linearity with human blood samples.
The specificity of this human osteocalcin ELISA also enables direct assay of human osteocalcin in osteoclast culture supernatant, differentiated bone marrow osteoblasts, and mesenchymal stem cells cultured in medium containing FBS. The detection antibody in this kit specifically recognizes the osteogenic marker Gla at position 17, allowing direct measurement of Gla-type (active type) osteocalcin in bone (primarily hydroxyapatite) matrix.
Antibodies for Osteocalcin Detection
Monoclonal Anti-Human Undercarboxylated Osteocalcin (Clone GluOC4-5; Cat. # M171) was raised against human osteocalcin peptide and specifically recognizes human osteocalcin with decarboxylated glutamic acid residues. This antibody does not recognize Gla-type osteocalcin. Monoclonal Anti-Human Osteocalcin (Clone 5-12H; Cat. # M184) was obtained by fusing mouse myeloma cell-line P3U1 with C57BL6 mouse spleen cells following immunization with keyhole limpet hemocyanin (KLH) conjugated to human osteocalcin peptide (amino acid residues 1–6). This monoclonal antibody was harvested from severe combined immunodeficiency (SCID) mouse ascitic fluid, and is useful for detection of full-length human osteocalcin.