The predominant component of immunoreactiveACTH in the plasma of adrenalectomizednormal mice and of mice bearing the adrenotropicmouse pituitary tumor, AtT-20, and in extractsof the normal mouse pituitary and pituitary tumor, hasan elution volume on Sephadex G-50 gel filtrationapproximately midway between the void volume andthe elution volume of human ACTH (1–39 peptide).The tumor extracts are shown to contain, in addition tothis intermediate ACTH, 2 other components of immunoreactiveACTH, one which coelutes with I3IIlabeledalbumin (big ACTH) and the other with[125I]hACTH (little ACTH). Big and intermediateACTH are urea-stable. Controlled tryptic digestionof mouse-tumor big ACTH results within 10 secondsin conversion to an intermediate component followedby continued loss of immunoreactivity. Underthe same conditions of tryptic digestion of intermediateACTH, there is only continuous loss of immunoreactivitywith no change of hormonal form. Thesefindings strengthen the hypothesis that mouse intermediateACTH is not a precursor for little ACTH. (Endocrinology97: 1308, 1975)

This content is only available as a PDF.
You do not currently have access to this article.