Table 1.
Insulin Growth Factor 1 (IGF1) | Binds IGF1R and hybrid receptors |
Insulin Growth Factor 2 (IGF2) | Binds IGF1R, IGF2R, IR-A and hybrid receptors |
Insulin | Binds IR-A, IR-B and IGF1R |
Insulin Growth Factor Receptor 1 (IGF1R) | Binds IGF1 and IGF2 with high affinity, and insulin with low affinity |
Insulin Growth Factor 2/Mannose-6-phosphate Receptor (IGF2/M6P-R or IGF2R) | Binds IGF2 Lacks intracellular signaling |
Insulin Receptor A (IR-A) | Lacks exon 11 (splice variant) Binds insulin and IGF2 with high affinity |
Insulin Receptor B (IR-B) | Contains exon 11 (splice variant) Binds insulin with high affinity |
IGF1R/IR-A | Hybrid Receptor |
IGF1R/IR-B | Hybrid Receptor |
IGF binding protein 1–6 (IGFBP1-6) | Bind IGF1 and IGF2, forming tertiary complexes with IGFALS and prolonging growth factors half-life. |
IGF binding protein 7–8 (IGFBP7-8) | Bind IGF1 with low affinity |
Acid-labile subunit (IGFALS) | 85 KD protein, member of leucin-rich repeats superfamily. Prolongs half-life of IGFBP3/5 and IGF1 binary complexes. |