Table 1.

Comparison of cloned facilitated urea transporters^a

Isoform^b	Synonyms	Species	Tissue^c	MW (kD)^d	Reference
UT-A1	UT1	Rat	Kidney	96	(45)
UT-A2	UT2	Rabbit, rat, human	Kidney	43	(31, 38, 39, 41)
UT-A3		Rat	Kidney	45	(46)
UT-A4		Rat	Kidney	43	(46)
UT-B1	HUT11, Rach1, UT3	Human, rat	Bone marrow, kidney	42 to 43	(59, 61, 135)
UT-B2	UT11	Rat	Brain	45	(60)

↵ ^a MW, molecular weight.
↵ ^b Isoform names are based on the systematic nomenclature for urea transporters proposed in reference 11.
↵ ^c Indicates tissue from which this isoform was originally cloned.
↵ ^d Predicted molecular mass based on amino acid sequence.