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.
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.