Studies on Pituitary Lactogenic Hormone. The Primary Structure of the Porcine Hormone*

The complete amino acid sequence of porcine lactogenic hormone has been elucidated. It consists of 199 amino acid residues with three disulfide bridges formed by residues 4-11, 58-174, and 191-199. The two tryptophan residues are in positions 91 and 150. A high degree of homology exists between the known structure of ovine prolactin and the porcine lactogenic hormone. This led to a re-examination of residues 82-90 in the ovine prolactin structure, where an extra leucine was found in position 88.