Metabolic Stability and the Impact of Binding Protein Evasion

Journal Context: Journal of Endocrinology / PubMed | Identifiers: DOI: 10.1677/joe.0.1240117 / PMID: 2179379

Principal Investigators: Ballard, F. J., Francis, G. L., Ross, M., Bagley, C. J., & Wallace, J. C. (Cooperative Research Centre for Tissue Growth and Repair, Adelaide, Australia)

Methodology: Comparative in vitro and ex vivo tracking measuring the biological survival time and protein synthesis potency of native IGF-1 against the modified Long R3 IGF-1 variant inside cell serum arrays containing dense concentrations of neutralizer proteins (IGFBPs).

Key Findings: Native IGF-1 was bound and deactivated almost immediately by serum binding proteins. In stark contrast, IGF-1 LR3 completely resisted binding protein neutralization, remaining fully active in the testing environment. Because it evaded these inhibitory proteins, IGF-1 LR3 demonstrated a $4$-to-$10$-fold increase in biological potency, driving a continuous, long-term stimulation of protein synthesis networks in muscle cell lines.