Proinsulin C-peptide interaction with protein tyrosine phosphatase 1B demonstrated with a labeling reaction.
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.
Jägerbrink
Theres
T
Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.
Lindahl
Emma
E
Shafqat
Jawed
J
Jörnvall
Hans
H
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*
D002096:C-Peptide; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1