Insulin-like Growth Factor-Binding Protein-6 (IGFBP-6)

Enzyme-linked immunoassay (ELISA) for the determination of Insulin-like Growth Factor 6 (IGFBP-6) in serum, plasma, cell culture medium, and other body fluids. For research use only, not for use in diagnostic procedures.<br><br>

The Insulin-like Growth Factor 6 (IGFBP-6) is part of the IGF-System which consists of several binding proteins (1-6) and IGF-I and –II. The Insulin-like Growth Factors are involved in the control of human growth and regulated themselves by their binding proteins. The IGFBPs show high amino acid sequence homology, they have conserved N- and C-terminal domains which are involved in IGF-binding. In contrast the central linker region is highly variable. This region is not directly involved in IGF-binding but influences stability and localization of the IGFBP / IGF complex and can be modified by glycosylation and phosphorylation.<br><br>

IGFBP-6 a protein of 213 amino acids and about 34 kDa is somewhat special because of only three disulphide bridges in the C-terminal domain, resulting in a significantly higher affinity (50fold) for IGF-II than IGF-I. Further IGFBP-6 can be O-glycosylated and is cleaved by cathepsin-D-like acid protease, neutral serine protease as well as MMP-2/-7/-9/-12.<br><br>

Main proposed function of IGFBP-6 is the regulation of the biological availability of IGF-II and thereby it influences cell proliferation, differentiation, migration and survival. Further IGF-independent as well as intra- and nuclear actions of IGFBP-6 are discussed. IGF-independent actions might be transmitted by prohibitin-2 as a potential cell surface receptor. Physiologically IGFBP-6 might be involved in senescence, angiogenesis and cancer. But a clear clinical indication for measurement of plasma IGFBP-6 needs to be determined (Bach, 2015).