Contribution of residues A54 and L55 of the human insulin-like growth factor-II (IGF-II) A domain to Type 2 IGF receptor binding specificity.
The underlying specificity of the interaction between insulin-like growth factor-II (IGF-II) and mammalian Type 2 insulin-like growth factor/cation-independent mannose 6 phosphate receptor (IGF2R) is not understood. We have mutated residues A54 and L55 of IGF-II in the second A domain helix to arginine (found in the corresponding positions of IGF-I) and measured IGF2R binding. There is a 4- and 3.3-fold difference in dissociation constants for A54R IGF-II and L55R IGF-II, respectively, and a 6.6-fold difference for A54R L55R IGF-II compared with IGF-II as measured by BlAcore analysis using purified rat IGF2R. This is also confirmed using cross-linking and soluble rat placental membrane receptor binding assays. Binding to the type I IGF receptor (IGF1R) and IGF binding protein-2 (IGFBP-2) is not altered. We can, therefore, conclude that residues at positions 54 and 55 in IGF-II are important for and equally contribute to IGF2R binding.
Forbe
B E
BE
Department of Biochemistry, Cooperative Research Centre for Tissue Growth and Repair, University of Adelaide, SA, Australia. briony.forbes@adelaide.edu.au
McNeil
K A
KA
Scott
C D
CD
Surinya
K H
KH
Cosgrove
L J
LJ
Wallace
J C
JC
D000818:Animals; D002412:Cations; D002462:Cell Membrane / Q000378:metabolism; D003432:Cross-Linking Reagents / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007335:Insulin-Like Growth Factor II / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D007700:Kinetics; D008024:Ligands; D008958:Models, Molecular; D009154:Mutation; D010455:Peptides / Q000737:chemistry; D010920:Placenta / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000378:metabolism; D051381:Rats; D017526:Receptor, IGF Type 1 / Q000737:chemistry / Q000378:metabolism; D017527:Receptor, IGF Type 2 / Q000737:chemistry* / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D013997:Time Factors
D002412:Cations; D003432:Cross-Linking Reagents; D008024:Ligands; D010455:Peptides; D011506:Proteins; D017527:Receptor, IGF Type 2; D011994:Recombinant Proteins; D007335:Insulin-Like Growth Factor II; D017526:Receptor, IGF Type 1