In addition, neither 3',5'-AMP nor ACTH stimulated the transformation of [7a-3H]pregnenolone (3/3-hydroxy-5-pregnen-3-one) or [7-3H]progesterone (4-pregnene-3,20-dione) to corticosteroids. The results indicate that both 3',5'-AMP and ACTH stimulate at the same site in the biosynthetic pathway for corticosteroids, i.e., between cholesterol and pregnenolone, and suggest that 3 ',5 '-AMP is an obligatory intermediate in the action of ACTH.

No abstract

Rat liver and kidney mitochondria labeled in vivo with radioactive leucine or valine were fractionated to provide a number of fractions that are reasonably well-recognized biochemical entities. The specific activities of the proteins of these fractions were compared to the specific activity of the unfractionated mitochondrial protein at times varying from 2 min to 8 hr after injection of the labeled amino acid. At short times the specific activities of the water-soluble proteins and the fraction containing cytochrome c were sig-

No abstract