Abstract
Somatostatin (SRIF) is a 14-residue peptide hormone synthesized in the hypothalamus and pancreatic islets. SRIF-14 and an N-terminally extended form, SRIF-28, are generated by the proteolytic processing of an approx. 102-residue precursor prosomatostatin (proSRIF) at a single set of paired basic residues (Arg-Lys) and at a monobasic (Arg) site respectively. Previous work in our laboratory demonstrated that the propeptide of SRIF mediates intracellular sorting; we suggested that this information resides in the prohormone structure. To identify putative sorting domains we have investigated structural features of recombinant anglerfish proSRIF-II purified from Escherichia coli. Two species of proSRIF-II were obtained: a monomeric form and a disulphide-linked dimer. CD analyses revealed that monomeric proSRIF-II lacks appreciable periodic secondary structure; however, on slow heating (2°C/min) and cooling, it assumed a predominantly α-helical conformation. When subjected to a second heating-and-cooling cycle, the α-helical conformation was maintained. In contrast, the dimeric form of proSRIF-II was predominantly α-helical and its helicity did not increase in response to heating and recooling. Our results suggest that proSRIF-II might exist in several different folding intermediate states.
Original language | English (US) |
---|---|
Pages (from-to) | 275-282 |
Number of pages | 8 |
Journal | Biochemical Journal |
Volume | 334 |
Issue number | 1 |
DOIs | |
State | Published - Aug 15 1998 |
ASJC Scopus subject areas
- Biochemistry
- Molecular Biology
- Cell Biology