ðə stˌɛɹɔɪdoʊdʒˈɛnɪk ɐkjˈuːt ɹˈɛɡjʊlətˌoːɹi pɹˈoʊtiːn, kˈɑːmənli ɹᵻfˈɜːd tʊ æz sənt ˌeɪˈɑːɹ stˈɑːɹd wˈʌn, ɪz ɐ tɹˈænspoːɹt pɹˈoʊtiːn ðæt ɹˈɛɡjʊlˌeɪts kəlˈɛstɚɹˌɑːl tɹˈænsfɜː wɪðˌɪn ðə mˌaɪɾəkˈɑːndɹiə, wˌɪtʃ ɪz ðə ɹˈeɪtlˈɪmɪɾɪŋ stˈɛp ɪnðə pɹədˈʌkʃən ʌv stˈɛɹɔɪd hˈoːɹmoʊnz.
The steroidogenic acute regulatory protein, commonly referred to as StAR (STARD1), is a transport protein that regulates cholesterol transfer within the mitochondria, which is the rate-limiting step in the production of steroid hormones.