Figure 17.3 A subunit of pyruvate carboxylase. Biotin, covalently attached to the biotin carboxyl carrier domain, transports CO2 from the biotin carboxylase active site to the pyruvate carboxylase active site of an adjacent subunit.
[Information from G. Lasso, L. P. C. Yu, D. Gil, S. Xiang, L. Tong, and M. Valle, Structure 18:1300–1310, 2010.]