ond rial ▁rib os om al ▁prote ins ▁are ▁encoded ▁by ▁nuclear ▁gen es ▁and ▁help ▁in ▁protein ▁synth esis ▁within ▁the ▁mit och ond r ion . ▁M ito ch ond rial ▁rib os om es ▁( m itor ib os om es ) ▁consist ▁of ▁a ▁small ▁ 2 8 S ▁sub unit ▁and ▁a ▁large ▁ 3 9 S ▁sub unit . ▁They ▁have ▁an ▁estimated ▁ 7 5 % ▁protein ▁to ▁r R NA ▁composition ▁compared ▁to ▁pro k ary otic ▁rib os om es , ▁where ▁this ▁ratio ▁is ▁revers ed . ▁Another ▁difference ▁between ▁m amm al ian ▁mit or ib os om es ▁and ▁pro k ary otic ▁rib os om es ▁is ▁that ▁the ▁latter ▁contain ▁a ▁ 5 S ▁r R NA . ▁Among ▁different ▁species , ▁the ▁prote ins ▁compr ising ▁the ▁mit or ib os ome ▁differ ▁greatly ▁in ▁sequence , ▁and ▁sometimes ▁in ▁bio chem ical ▁properties , ▁which ▁prevents ▁easy ▁recognition ▁by ▁sequence ▁hom ology . ▁This ▁gene ▁enc odes ▁a ▁ 3 9 S ▁sub unit ▁protein . ▁De let ions ▁in ▁this ▁gene ▁may ▁contribute ▁to ▁the ▁et i ology ▁of ▁vel o - card io - fa cial ▁synd rome ▁and ▁Di Ge orge ▁synd rome . ▁ ▁References ▁ ▁Further ▁reading ▁ ▁Category : R ib os om al ▁prote ins <0x0A> </s> ▁John ▁Mer ritt ▁was ▁a ▁British ▁film ▁and ▁television ▁editor , ▁writer , ▁and ▁director . ▁He ▁was ▁born ▁on ▁June ▁ 9