Wild type and mutant IGF-1R constructs.

<p>A. IGF-1R is a heterodimeric receptor with two identical ß-subunit and two identical α-subunits. The α-subunit is completely extracellular, while the ß-subunit spans the membrane. The intracellular portion (residues 931–1337) has a TK domain with intrinsic kinase activity. Important tyrosine residues in the TK domain, know as activation loop, are (Y1131, Y1135 and Y1136) shown in green. Tyrosine residue Y950 (in blue) is, when phosphorylated, a docking site for binding of signaling molecules. Other important regions of the receptor are the ATP binding site (K1003) and the C-terminal domain important for phosphorylation and signaling, respectively. B. The expression of all IGF-1R variants were investigated on cells growing under basal conditions (complete medium supplemented with serum). Cell lysates were subjected to western blotting using antibodies to IGF-1R (β-subunit) and GAPDH (loading control).