1. Vitamin B12 metabolism in algal and human cells.
Vitamin B12 metabolism in algal and human cells. (A) Structure of vitamin B12 (cobalamin). The molecule consists of a highly modified tetrapyrrole ring to which a lower nucleotide loop is attached. R can be either a methyl (Me) or an adenosyl (Ado) group. (B) Genes involved in vitamin B12 metabolism in eukaryotic cells. Those genes responsible for each step are shown, followed by the symbol ○ or ▪ indicating the presence of the gene in different algae (see Fig. 2 for the key). Cobalamin derivatives (Cbl) and the oxidation state of cobalt are shown. Cobalamin containing Co3+ (CblIII) is converted to methylcobalamin, while cobalamin containing Co+ (CblI) is converted to adenosylcobalamin.
Martin T. Croft et al. Eukaryotic Cell 2006; doi: /EC