IGFBP, short for insulin-like growth factor binding protein, refers to a group of carrier proteins that bind to insulin-like growth factors (IGFs) in the bloodstream. These proteins play a pivotal role in regulating and modulating the biological activities of IGFs, which are peptide hormones that stimulate growth and development throughout the body.
IGFBPs are primarily synthesized and secreted by a wide range of tissues including the liver, bone, and placenta. They exert their function by binding to IGFs, specifically IGF-1 and IGF-2, forming a stable complex. This complex not only helps to prolong the half-life of IGFs in the circulation but also modulates their biological actions.
The binding of IGFBPs to IGFs controls their distribution, availability, and receptor binding affinity. It regulates the levels of free IGFs, as these proteins can sequester the IGFs and prevent their binding to their respective receptors. By doing so, IGFBPs can either enhance or inhibit IGF signaling, thereby regulating processes such as cell growth, differentiation, metabolism, and survival.
Furthermore, IGFBPs also possess IGF-independent functions. These include interactions with cellular components such as extracellular matrix proteins, cell surface receptors, and other binding partners, thus impacting cellular processes beyond their involvement with IGF regulation.
Overall, IGFBPs are important regulatory proteins that modulate the activity and availability of IGFs in the body, playing a vital role in the regulation of growth, development, and numerous physiological processes.
