title: Proinsulin C-peptide interaction with protein tyrosine phosphatase 1B demonstrated with a labeling reaction.
abstract: Based on nickel-catalyzed cross-labeling where binding partners become biotinylated, we have studied molecular interactions with an N-terminally fused GGH-tag proinsulin C-peptide. Since C-peptide has been reported to influence phosphatase activity in intact cells, we employed this method to study possible binding of the peptide to protein tyrosine phosphatase 1B (PTP-1B). C-peptide was found to interact with PTP-1B (and for control, also with antibodies to C-peptide), as did also the N- and C-terminal fragments of C-peptide which have sequence similarities with PTP-1B binding proteins. The labeling data combined with enzyme activity analysis indicate a functional interaction between acidic regions of C-peptide and specific sites of PTP-1B. Results highlight the importance of possible phosphatase/C-peptide roles in diabetes, and the usefulness of the cross-labeling reaction also for acidic peptides like C-peptide.
authors.affiliation: Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Theres
authors.initials: T
authors.lastname: Jägerbrink
authors.forename: Emma
authors.initials: E
authors.lastname: Lindahl
authors.forename: Jawed
authors.initials: J
authors.lastname: Shafqat
authors.forename: Hans
authors.initials: H
authors.lastname: Jörnvall
mesh_terms: D019921:Biotinylation; D002096:C-Peptide / Q000737:chemistry / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D002096:C-Peptide; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1