DIFFERENCES IN SYNTHESIS AND PROCESSING OF ACTH/ENDORPHIN PEPTIDES IN PRIMARY CULTURES OF ANTERIOR AND INTERMEDIATE LOBES OF THE PITUITAR

Abstract

The focus of research in our laboratory over the few years has been the regulation of synthesis, processing, and release of the ACTH/LPH family of peptides. These peptides are derived from a common precursor protein that is found in both the anterior and intermediate lobes of the pituitary (Roberts et al., 1978) and in the hypothalamus (Liotta et al., 1979). In the anterior lobe this protein gives rise to α (1–39) ACTH, β-lipotropin (β-LPH) and an N-terminal fragment of undefined function. In addition, a variety of intermediate lobe pituitary peptides can be derived from the precursor by further processing of ACTH and β-LPH. In this paper we compare the structure of the precursor in the anterior and intermediate lobes of mouse and rat pituitary. Processing of the precursor to its constituent hormones is then contrasted in primary cultures of anterior and intermediate lobe cells using pulse label and pulse chase techniques with radioactive amino acids and sugars.