▁and ▁becomes ▁ph osph ory l ated . ▁ ▁The ▁ph osph ate ▁is ▁sh utt led ▁onto ▁various ▁sign alling ▁domains ▁until ▁it ▁wind s ▁up ▁on ▁Arc A , ▁the ▁response ▁reg ulator . ▁ ▁The ▁ph osph ory l ated ▁Arc A ▁is ▁then ▁able ▁to ▁act ▁as ▁either ▁an ▁activ ator ▁or ▁repr essor ▁for ▁various ▁met abol ic ▁gen es . ▁ ▁So , ▁when ▁o xygen ▁is ▁low , ▁then ▁gene ▁products ▁that ▁util ize ▁o xygen ▁will ▁be ▁repr essed , ▁while ▁gen es ▁that ▁do ▁not ▁require ▁o xygen ▁will ▁be ▁up reg ulated . ▁ ▁Category : H em op rote ins ▁Category : Cell ular ▁resp iration <0x0A> </s> ▁Ch ol ester ol ▁side - chain ▁cle av age ▁en zym e ▁is ▁ ▁commonly ▁referred ▁to ▁as ▁P 4 5 0 s cc , ▁where ▁" s cc " ▁is ▁an ▁ac ron ym ▁for ▁side - chain ▁cle av age . ▁P 4 5 0 s cc ▁is ▁a ▁mit och ond rial ▁en zym e ▁that ▁catal y zes ▁conversion ▁of ▁ch ol ester ol ▁to ▁preg nen ol one . ▁This ▁is ▁the ▁first ▁reaction ▁in ▁the ▁process ▁of ▁ster oid ogen esis ▁in ▁all ▁m amm al ian ▁t issues ▁that ▁special ize ▁in ▁the ▁production ▁of ▁various ▁ster oid ▁h orm ones . ▁ ▁P 4 5 0 s cc ▁is ▁a ▁member ▁of ▁the ▁cy to chrome ▁P 4 5 0 ▁super family ▁of ▁en zym