Calpain proteolysis of insulin-like growth factor binding protein (IGFBP) -2 and -3, but not of IGFBP-1.
Calpains are cytoplasmic Ca(2+)-regulated cysteine proteases that may regulate insulin-like growth factor (IGF)-independent actions of insulin-like growth factor binding proteins (IGFBPs) through IGFBP proteolysis. In this study, [(125)I]-labeled IGFBP-2 and -3, but not IGFBP-1, were proteolyzed by Ca(2+)-activated m-calpain in vitro. Degradation of higher concentrations of the recombinant proteins IGFBP-2 and -3 by m-calpain was dose-dependent, but was terminated within 20 min by autolysis. By subjecting proteolytic fragments to N-terminal amino acid sequence analysis, the primary cleavage sites in IGFBP-2 and -3 were localized to the non-conserved central linker regions. Using the biosensor technique, in vitro binding of m-calpain to IGFBP-3 was demonstrated to be a Ca(2+)-dependent reaction with a rapid on/off rate.
Berg
Ulrika
U
Department of Woman and Child Health, Pediatric Endocrinology and Diabetes Unit, Karolinska Institute, Astrid Lindgren Children's Hospital, S-171 76 Stockholm, Sweden.
Bang
Peter
P
Carlsson-Skwirut
Christine
C
D015374:Biosensing Techniques; D002118:Calcium / Q000494:pharmacology; D002154:Calpain / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D018970:Insulin-Like Growth Factor Binding Protein 1 / Q000378:metabolism; D018971:Insulin-Like Growth Factor Binding Protein 2 / Q000378:metabolism; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000378:metabolism; D018969:Insulin-Like Growth Factor Binding Proteins / Q000378:metabolism*; D011499:Protein Processing, Post-Translational / Q000187:drug effects*; D013997:Time Factors
D018970:Insulin-Like Growth Factor Binding Protein 1; D018971:Insulin-Like Growth Factor Binding Protein 2; D018972:Insulin-Like Growth Factor Binding Protein 3; D018969:Insulin-Like Growth Factor Binding Proteins; D002154:Calpain; D002118:Calcium