Other organs like mature petiole, stem young and mature roots appears to have similar levels of FK protein, however, the activity in mature root is one third of the specific observed in the other tissues (Fig. 3B and C).
The fructokinase antibodies do not recognize any other protein, but the activity assay is not so specific.
Therefore, differences between FK protein and FK specific activity can be in part attributed to the activity of some other hexokinases.