5 ′ UT R ▁and ▁encode ▁small , ▁unknown ▁prote ins ▁that ▁contain ▁D U F 4 2 7 8 ▁and ▁are ▁put ative ▁regul ators ▁of ▁gl ut am ine ▁synth et ase . ▁This ▁hypothesis ▁is ▁supported ▁by ▁the ▁finding ▁that ▁expression ▁of ▁the ▁D U F 4 2 7 8 - cont aining ▁gl ut am ine ▁synth et ase ▁in hib itory ▁factor ▁IF 1 7 ▁encoding ▁gene ▁g if B ▁was ▁shown ▁to ▁be ▁reg ulated ▁by ▁the ▁struct ur ally ▁related ▁g ln A ▁R NA ▁mot if . ▁ ▁Down stream - pe pt ide ▁R N As ▁overlap ▁a ▁predicted ▁non - c oding ▁R NA ▁called ▁y fr 6 ▁that ▁is ▁over ▁ 2 0 0 ▁nucle ot ides ▁in ▁length , ▁but ▁it ▁was ▁proposed ▁that ▁only ▁the ▁up stream ▁region ▁( cor respond ing ▁to ▁the ▁Down stream - pe pt ide ▁mot if ) ▁functions ▁as ▁an ▁R NA ▁structure . ▁A ▁distinct ▁predicted ▁non - c oding ▁R NA ▁called ▁y fr 1 4 ▁over laps ▁both ▁y fr 6 ▁and ▁Down stream - pe pt ide ▁R N As . ▁However , ▁it ▁is ▁unclear ▁whether ▁y fr 6 ▁or ▁y fr 1 4 ▁have ▁any ▁function ▁beyond ▁the ▁now - est ab lished ▁role ▁of ▁the ▁Down stream - pe pt ide ▁rib os w itch . ▁ ▁References ▁ ▁External ▁links ▁▁▁ ▁Category : C is - reg ul atory ▁R NA ▁elements ▁Category : R ib