IGFBP6 Human

IGFBP-6 is encoded by the IGFBP6 gene, which produces a 240 amino acid precursor protein. This precursor includes a 24 amino acid signal peptide that is processed to generate the mature 216 amino acid protein . The mature protein is O-glycosylated, which is essential for its function and stability.

Recombinant human IGFBP-6 (rhIGFBP-6) is synthesized using COS-7 monkey kidney cells that are transiently transfected with a eukaryotic expression vector containing a complementary DNA for IGFBP-6. This recombinant protein is similar to IGFBP-6 purified from human cerebrospinal fluid in terms of IGF binding and O-glycosylation .

IGFBP-6 primarily functions by binding to IGF-II, inhibiting its interaction with IGF receptors. This binding inhibits IGF-II-induced differentiation of cells, such as L6A1 myoblasts, in a dose-dependent manner. Interestingly, IGFBP-6 does not affect IGF-I-induced differentiation, even when present in a five-fold molar excess .

The inhibition of IGF-II-induced differentiation by IGFBP-6 is significant because it highlights the protein’s role in modulating IGF actions. The protein remains intact and soluble, inhibiting IGF-II-induced differentiation without being associated with cell lysates or extracellular matrix .

IGFBP-6 is expressed in various tissues, including ovarian cells, prostatic cells, and fibroblasts. It is predominantly found in cerebrospinal fluid (CSF) and serum . The expression of IGFBP-6 in these tissues suggests its involvement in various physiological processes, particularly those related to growth and differentiation.

Recombinant human IGFBP-6 is used in various research applications to study its role in modulating IGF actions. The fidelity of the IGFBP-6 expression system enables researchers to investigate how structural modifications of the protein affect its function . Additionally, IGFBP-6 is used in enzyme-linked immunosorbent assays (ELISAs) to detect and quantify its levels in serum, plasma, and cell culture media .