Complex sentence: StAR is located in the mitochondria of the adrenal and gonadal glands and increases with steroid production, however it has not been found in other tissue that can produce steroids, such as the brain and placenta.
Split into simpler sentences: StAR is located in the mitochondria of the adrenal and gonadal glands and increases with steroid production. StAR has not been found in other tissue that can produce steroids, such as the brain and placenta.