kəlˈɛstɚɹˌɑːl nˈiːdz təbi tɹænsfˈɜːd fɹʌmðɪ ˈaʊɾɚ mˌaɪɾəkˈɑːndɹɪəl mˈɛmbɹeɪn tə ðɪ ˈɪnɚ mˈɛmbɹeɪn wˌɛɹ sˈaɪɾəkɹˌoʊm pˈiː fˈoːɹhˈʌndɹɪd fˈɪfti ˌɛssˌiːsˈiː ˈɛnzaɪm sˌiːwˌaɪpˈiː ɪlˈɛvən ˈeɪ wˈʌn klˈiːvz ðə kəlˈɛstɚɹˌɑːl sˈaɪd tʃˈeɪn, wˌɪtʃ ɪz ðə fˈɜːst ˌɛnzɪmˈæɾɪk stˈɛp ɪn ˈɔːl stˈɛɹɔɪd sˈɪnθəsˌɪs.
Cholesterol needs to be transferred from the outer mitochondrial membrane to the inner membrane where cytochrome P450scc enzyme (CYP11A1) cleaves the cholesterol side chain, which is the first enzymatic step in all steroid synthesis.