Table 1

The human sulfotransferase enzyme family

SULT1A1	SULT1A2	SULT1A3	SULT1B1	SULT1C1^1-a	SULT1C2^1-a ^1-b	SULT1E1	SULT2A1	SULT2B1a	SULT2B1b
Simple phenols	Simple phenols	Catecholamines	Simple phenols	N-Hydroxy-2-acetylaminofluorene	?	Estrone	DHEA	DHEA	DHEA
Catechols	Catechols	Catechols	Catechols			Estradiol	Pregnenolone	?	?
Minoxidil		Tyramine	Iodothyronines			Estriol	Cholesterol
Paracetamol		5-Hydroxytryptamine				17α-Ethinylestradiol	Cortisol
Hydroxyarylamines		Salbutamol				Equilenin	Benzylic alcohols of PAHs
Iodothyronines		Isoprenaline				Diethylstilbestrol	Testosterone
		Dobutamine				Thyroxine	Bile salts

A novel SULT gene has been identified through the chromosome 22 sequencing project that shares approximately 30% amino acid sequence identity with other human SULTs. Provisional name, SULT4A1, EMBL accession numbers: CAB09788, AF115311. The function is as yet unknown.

↵1-a The SULT1C enzymes are named here on the basis that SULT1C1 is the ortholog of the rat SULT1C1 enzyme—the first of this family to be discovered (Nagata et al., 1993). The enzyme labeled SULT1C2 here is coded by the first human SULT1C cDNA to be cloned, which the authors named SULT1C1 (Her et al., 1997). The following EMBL accession numbers relate to the nomenclature as stated here: SULT1C1, AF055584; SULT1C2, U66036.
↵1-b SULT1C2 appears to be essentially a “dead” enzyme, i.e., little or no activity toward any standard substrate. It has an amino acid change in a conserved residue in the active site of the enzyme (Tyr₂₄₁Arg), which may explain this.