Diagram outlining the biosynthetic pathway of UDP-Araf and its transport across the Golgi membrane of plants. Characterized pathway members are identified by the gene names: UUAT, UDP-uronic acid transporter; UXT, UDP-Xyl transporter; RGP, UDP-Ara mutase (reversibly glycosylated polypeptide); ARA1, L-arabinokinase; USP, UDP-sugar pyrophosphorylase; UAfT, UDP-Araf transporter; UGE, UDP-glucose 4-epimerase; UXE, UDP-Xyl 4-epimerase; and UGD, UDP-glucose 6-dehydrogenase.