PRIMARY STRUCTURE AND EVOLUTION OF NEUROPHYSINS *

This paper will focus on the subject of the available primary structural data on neurophysins. An attempt will be made to glean from these data certain insights into the evolution, conformation, and function of this group of proteins. In addition, the relationship between the structure of the neurophysins and other pituitary hormones and hormone-like proteins will be considered. The complete amino acid sequence of one of the porcine neurophysins (PNP-I) was described by Wuu et a1.I at about the same time that our laboratory reported the complete sequence of bovine neurophysin-I1 (BNP-II).Z Since that time, the covalent structure of BNP-I1 has been secured by assigning all of its disulfide bonds.3 Moreover, the N-terminal 5 0 amino acid residues of a second bovine neurophysin, BNP-I, have been reported," and the sequence of this protein has now been virtually completed and will be presented later in this confe ren~e .~ In addition, the N-terminal 54 amino acid residues of a human neurophysin (HNP-I) have been recently determined in our laboratory in collaboration with Cheng and Friesen,6 and we have secured a highly tentative complete sequence for HNP-I.S There are therefore available for comparison three complete neurophysin sequences (two bovine and one porcine), and four sequences of half the protein (two bovine, one porcine, and one human). These sequences are displayed in FIGURE 1. From these 335 amino acid residues (and the disulfide bond structure of one protein), a fragmentary picture of the evolutionary history of these proteins can be surmised.