Six sugar phosphate cyclase family members, their substrates and products, and their connections to the Pentose Phosphate Pathway. DOIS, 2-deoxy-scyllo-inosose synthase; EVS, 2-epi-valiolone synthase; EEVS, 2-epi-5-epi-valiolone synthase; DDGS, desmethyl-4-deoxygadusol synthase; aDHQS, aminodehydroquinate synthase; DHQS, 3-dehydroquinate synthase.