TABLE 4.

Putative proton binding sites in Sul1 and Sul2

Corresponding amino acid residues in Sul1 and Sul2 are indicated in the same row.

Sul1		Sul2		TMD
Predicted site	Mutant allele analyzed	Predicted site	Mutant allele analyzed
Asp-124	D124N	Asp-140		1
		Asp-305	D305N	7
Glu-406		Glu-422		9
Glu-427	E427Q	Glu-443	E443Q	10
Asp-483	D483N			12
Asp-503		Asp-519	D519N	13
Glu-538	E538Q			14