1T0C: Solution Structure of Human Proinsulin C-Peptide

Citation:
Abstract
The C-peptide of proinsulin is important for the biosynthesis of insulin, but has been considered for a long time to be biologically inert. Recent studies in diabetic patients have stimulated a new debate about its possible regulatory role, suggesting that it is a hormonally active peptide. We describe structural studies of the C-peptide using 2D NMR spectroscopy. In aqueous solution, the NOE patterns and chemical shifts indicate that the ensemble is a nonrandom structure and contains substructures with defined local conformations. These are more clearly visible in 50% H2O/50% 2,2,2-trifluoroethanol. The N-terminal region (residues 2-5) forms a type I beta-turn, whereas the C-terminal region (residues 27-31) presents the most well-defined structure of the whole molecule including a type III'beta-turn. The C-terminal pentapeptide (EGSLQ) has been suggested to be responsible for chiral interactions with an as yet uncharacterized, probably a G-protein-coupled, receptor. The three central regions of the molecule (residues 9-12, 15-18 and 22-25) show tendencies to form beta-bends. We propose that the structure described here for the C-terminal pentapeptide is consistent with the previously postulated CA knuckle, believed to represent the active site of the C-peptide of human proinsulin.
PDB ID: 1T0CDownload
MMDB ID: 34502
PDB Deposition Date: 2004/4/8
Updated in MMDB: 2007/11
Experimental Method:
solution nmr
Source Organism:
Similar Structures:
Molecular Components in 1T0C
Label Count Molecule
Protein (1 molecule)
1
Insulin(Gene symbol: INS)
Molecule annotation
* Click molecule labels to explore molecular sequence information.

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