Title : Primary structure of the major human pituitary
pro-opiomelanocortin NH2-terminal
glycopeptide
Abstract :
- Evidence for an aldosterone-stimulating activity
- The isolation and complete purification of a human glycopeptide representing the major immunoreactive form of the pituitary NH2-terminal segment of pro-opiomelanocortin is presented
- The complete sequence of this peptide was determined following CNBr fragmentation and it is shown to be 76 amino acids long
- It bears an O-glycosylation site at Thr 45 and an N-glycosidic linkage at Asn 65
- Compared to the reported genomic DNA sequence (Chang, A. C. Y., Cochet, M., and Cohen, S. N. ( 1980) Proc
- Natl. Acad
- Sci
- U. S. A. 77, 4890-4894), one variation exists, namely Arg 22 replacing Gly 22
- Two disulfide bridges linking Cys 2 to 8 and Cys 20 to 24 have been determined
- Based on the sequence and disulfide bridge localization, a large degree of homology exists between the NH2-terminal sequence of the human peptide and all calcitonins, especially porcine calcitonin
- The human NH2-terminal peptide is shown to stimulate the release of aldosterone from isolated cells of a human adrenal tumor, in at least equipotency to adrenocorticotropic hormone and the porcine NH2-terminal analogue, which is 100 times more potent than angiotensin II
- Finally , this reported sequence completes that of the human DNA which was lacking the first 19 amino acids due to the presence of a 2-kilobase intron