Structural and mutational analyses of decarboxylated osteocalcin provide insight into its adiponectin-inducing activity.
Mizuguchi, M., Yokoyama, T., Otani, T., Kuribara, S., Nabeshima, Y., Obita, T., Hirata, M., Kawano, K.(2023) FEBS Lett 597: 1479-1488
- PubMed: 36976525 
- DOI: https://doi.org/10.1002/1873-3468.14618
- Primary Citation of Related Structures:  
8I74, 8I75, 8I76 - PubMed Abstract: 
An acidic environment in bone is essential for bone metabolism and the production of decarboxylated osteocalcin, which functions as a regulatory hormone of glucose metabolism. Here, we describe the high-resolution X-ray crystal structure of decarboxylated osteocalcin under acidic conditions. Decarboxylated osteocalcin at pH 2.0 retains the α-helix structure of native osteocalcin with three γ-carboxyglutamic acid residues at neutral pH. This implies that decarboxylated osteocalcin is stable under an acidic environment in bone. In addition, site-directed mutagenesis revealed that Glu17 and Glu21 are important for the adiponectin-inducing activity of decarboxylated osteocalcin. These findings suggest that the receptor of decarboxylated osteocalcin responds to the negative charge in helix 1 of osteocalcin.
Organizational Affiliation: 
Faculty of Pharmaceutical Sciences, University of Toyama, Toyama, Japan.