Figure 4.

Schematic diagram representing topology of two Slc14a facilitative urea transporters: UT-A1 and UT-B1. Various important residues are highlighted in each transporter: the asparagine (Asn) residues known to be important in glycosylation; the serine residues (Ser) known to be involved in the phosphorylation events that regulate transporter function; the cysteine (Cys) residues important in targeting the protein to the plasma membrane.