Ribose-5-phosphate isomerase and ribulose-5-phosphate kinase show apparent specificity for a specific ribulose 5-phosphate species.

Ribose-5-phosphate isomerase and ribulose-5-phosphate kinase appear to show specificity for a particular ribulose 5-phosphate species. The effect of this specificity will be channeling of ribulose 5-phosphate from the isomerase to the kinase during photosynthesis.