Osteocalcin (Bone Gla protein) (BGP) (Gamma-carboxyglutamic acid-containing protein)
1_MRALT 6_ LLALL 11_ ALAAL 16_ CIAGQ 21_ AGAKP 26_ SGAES 31_ SKGAA 36_ FVSKQ 41_ EGSEV 46_ VKRPR 51_ RYLYQ 56_ WLGAP 61_ VPYPD 66_ PLEPR 71_ REVCE 76_ LNPDC 81_ DELAD 86_ HIGFQ 91_EAYRR
1: Bone protein that constitutes 1-2% of the total bone protein, and which acts as a negative regulator of bone formation (PubMed:3019668, PubMed:6967872). Functions to limit bone formation without impairing bone resorption or mineralization (By similarity). It binds strongly to apatite and calcium (PubMed:6967872)
2: The uncarboxylated form acts as a hormone secreted by osteoblasts, which regulates different cellular processes, such as energy metabolism, male fertility and brain development. Regulates of energy metabolism by acting as a hormone favoring pancreatic beta-cell proliferation, insulin secretion and sensitivity and energy expenditure. Uncarboxylated osteocalcin hormone also promotes testosterone production in the testes: acts as a ligand for G protein-coupled receptor GPRC6A at the surface of Leydig cells, initiating a signaling response that promotes the expression of enzymes required for testosterone synthesis in a CREB-dependent manner. Also acts as a regulator of brain development: osteocalcin hormone crosses the blood-brain barrier and acts as a ligand for GPR158 on neurons, initiating a signaling response that prevents neuronal apoptosis in the hippocampus, favors the synthesis of all monoamine neurotransmitters and inhibits that of gamma-aminobutyric acid (GABA). Osteocalcin also crosses the placenta during pregnancy and maternal osteocalcin is required for fetal brain development