Function
Catalyzes a reaction of the Smirnoff-Wheeler pathway, the major route to ascorbate biosynthesis in plants. Acts as a phosphorylase rather than as a transferase. Uses preferentially GDP-L-galactose and GDP-D-glucose as substrates. Lower activity with GDP-L-fucose, very low activity with GDP-D-mannose, and no activity with UDP-D-glucose, UDP-D-galactose or ADP-D-glucose. Highly specific for inorganic phosphate as the guanylyl acceptor.
Sequence
MLLKIKRVPTVVSNYQKDETVEEGGCGRNCLSKCCINGARLPLYTCKNLDKSVGENTESPVTFLESLVIGEWEDRFQRGLFRYDVTACETKVIPGKYGFIAQLNEGRHLKKRPTEFRVDKVLQPFDGNKFNFTKVGQEELLFQFKASTNDDDSEIQFLASMPLDADNSPSVVAINVSPIEYGHVLLIPRVLDCLPQRIDHKSLLLALQMAAEADNPYFRLGYNSLGAFATINHLHFQAYYLAMQFPIEKASSLKITTTNNGVKISKLLNYPVRGLLVEGGNTIKDLADTVSDASVCLQNNNIPFNILISDSGKRIFLLPQCYAEKQALGEVSSTLLDTQVNPAVWEMSGHMVLKRKEDYEGASEEKAWRLLAEVSLSEERFREVNTMIFDAIGFSSHEEEEEEELEEQNSMNGGSFTIVHCPSVKEEAVSN