CORTICOTROPIN AND BETA-ENDORPHIN - CONSTRUCTION AND ANALYSIS OF RECOMBINANT DNA COMPLEMENTARY TO MESSENGER-RNA FOR THE COMMON PRECURSOR

A cDNA fragment synthesized from mouse mRNA (ACTH/LPH mRNA) that codes for the precursor polypeptide containing corticotropin (ACTH), β-lipoprotein (LPH), and several other peptides has been cloned in bacteria. The mRNA was enriched for ACTH/LPH mRNA translational activity (to about 75%) prior to cDNA synthesis. It appears to contain about 1200 bases, of which approximately 450 bases are not translated. The cloned DNA fragment is complementary to the region of the mRNA coding for the protein fragment β-LPH-(44-90); this contains all of the amino acids of [Met]-enkephalin (residues 61-65 of β-LPH), most of the amino acids of β-melanocyte-stimulating hormone, and all but the carboxy-terminal amino acid of β-endorphin. Based on assignment of the amino acid sequence of mouse β-LPH from the nucleic acid sequence, it appears that there is extensive homology of mouse β-LPH with human and porcine β-LPH. The data also establish the linkage between β-melanocyte-stimulating hormone and β-endorphin as a Lys-Arg sequence. It is hoped that this cloned DNA can be used as a probe to study the expression and structure of the ACTH/LPH gene.