Mutants of human insulin-like growth factor II with altered affinities for the type 1 and type 2 insulin-like growth factor receptor.
With the aim to produce insulin-like growth factors (IGF) with enhanced specificity for the type 1 or type 2 IGF receptors, three mutants of IGF II have been prepared and expressed in NIH-3T3 cells. IGF II mutated at Tyr27 to Leu and Glu showed a 25- and 54-fold decrease in affinity for the type 1 IGF receptor and a 3.4- and 9.2-fold decrease in affinity for the type 2 IGF receptor. IGF II mutated at Phe48 to Glu showed a 18-fold decrease in affinity for the type 2 IGF receptor and a 2.8-fold decrease in affinity for the type 1 IGF receptor. These affinities were measured in radioreceptor assays using type 1 or 2 IGF receptor overexpressing cells. Data obtained on receptor cross-linking and thymidine incorporation assays confirmed the results of the radioreceptor assays. It is concluded that mutations of Tyr27 preferentially decrease binding to the type 1 IGF receptor and of Phe48 to the type 2 IGF receptor, either by the loss of a residue involved in receptor binding or by preferentially destabilizing the region involved in receptor binding.
Bürgisser
D M
DM
Department of Biochemistry University of Zürich, Switzerland.
Roth
B V
BV
Giger
R
R
Lüthi
C
C
Weigl
S
S
Zarn
J
J
Humbel
R E
RE
D000595:Amino Acid Sequence; D001483:Base Sequence; D015153:Blotting, Western; D002460:Cell Line; D003432:Cross-Linking Reagents; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D007335:Insulin-Like Growth Factor II / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D011863:Radioimmunoassay; D011869:Radioligand Assay; D011956:Receptors, Cell Surface / Q000378:metabolism*; D017451:Receptors, Somatomedin; D013936:Thymidine / Q000378:metabolism
D003432:Cross-Linking Reagents; D011956:Receptors, Cell Surface; D017451:Receptors, Somatomedin; D007335:Insulin-Like Growth Factor II; D013936:Thymidine