Fig. 1.

Sequence alignment of Bacillus subtilis phoAIII, phoAIV gene products, Thermotoga maritima, and Escherichia coli alkaline phosphatases (APs). Residues associated with metal binding in the E. coli AP active sites are labeled with (↑). These residues are completely conserved in all four of these examples of AP, with the exception of D153H and K328W (mature E. coli AP numbering). The N-terminus of the B. subtilis phoAIII AP mature protein is indicated with (♦), the N-terminus of the B. subtilis phoAIV AP mature protein is indicated with (•), the N-terminus of the E. coli mature AP is labeled with (▴), and the serine nucleophile and conserved arginine are labeled with (▪).