Catalyzes the transfer of a glucuronic acid (GlcA) residue from UDP-glucuronate to mannose-alpha-1,3-glucose-beta-1,4-glucose-P-P-polyisoprenyl to form the lipid-linked tetrasaccharide GlcA-Man-Glc(2)-PP-Pol, with a glucuronic acid-beta-mannose linkage. Is involved in the biosynthesis of the exopolysaccharide xanthan, since it catalyzes the fourth glycosylation step in the assembly of the pentasaccharide-P-P-polyisoprenyl repeating unit of xanthan. alpha-D-Man-(1->3)-beta-D-Glc-(1->4)-alpha-D-Glc-1-di-trans,octa-cis-undecaprenyl diphosphate + UDP-alpha-D-glucuronate = beta-D-GlcA-(1->2)-alpha-D-Man-(1->3)-beta-D-Glc-(1->4)-alpha-D-Glc-di-trans,octa-cis-undecaprenyl diphosphate + H(+) + UDP Glycan biosynthesis; xanthan biosynthesis. Belongs to the glycosyltransferase 70 family. Truncated N-terminus.