The tetradecapeptide somatostatin (SS-14) is synthesized as part of a large precursor, preprosomatostatin (PPSS). Several different forms of PPSS have been characterized in various species. After cotranslational removal of the signal peptide from PPSS, the resulting prosomatostatins (PSSs) are subjected to specific posttranslational cleavages to release SS-14, somatostatin-28 (SS-28) and other peptides derived from the precursors.
The specific aims of this application include: Investigation of the bioactivity of a newly discovered hydroxylysine-containing form of SS-28, aSS-28, which is a demonstrated metabolic cleavage product of one form of PSS in anglerfish islets; Determination whether a single or separate prohormone converting endopeptidases (PCEs) cleave SS-14 and aSS-28 from anglerfish islet PSSs; Isolation and elucidation of the complete primary structures of PSS processing PCEs; Isolation and structure determination of a carboxypeptidase B-like (CPB) exopeptidase which is involved in PSS processing. Effects of aSS-28 on islets and dispersed islet cells will be examined by monitoring hormone release with RIAs. The PSS processing PCEs and CPB can be isolated by employing ion exchange and hydrophobic chromatography. Experiments will be performed to determine whether the anglerfish enzymes can cleave mammalian PSSs. Microsequencing procedures will be employed to obtain partial sequence information. Complete sequences of the PCEs and CPB will be obtained by applying recombinant DNA methodologies. The long term objectives are to determine the characteristics of PSS converting enzymes which render them specific. The process of characterizing the anglerfish islet converting enzymes will involve generation of probes which will be useful in screening mammalian tissues for similar enzymes. The results obtained from these studies will provide an informational base for further investigation of the mechanisms controlling PSS processing. Perturbations in these mechanisms could play a role in the etiology of some types of diabetes mellitus or other disease states. Once the normal mechanisms are understood, aberrations which lead to pathology could be more readily identified.
| Roth, W W; Mackin, R B; Spiess, J et al. (1991) Primary structure and tissue distribution of anglerfish carboxypeptidase H. Mol Cell Endocrinol 78:171-8 |
| Mackin, R B; Noe, B D; Spiess, J (1991) The anglerfish somatostatin-28-generating propeptide converting enzyme is an aspartyl protease. Endocrinology 129:1951-7 |
| Mackin, R B; Noe, B D; Spiess, J (1991) Identification of a somatostatin-14-generating propeptide converting enzyme as a member of the kex2/furin/PC family. Endocrinology 129:2263-5 |
