Insulin-like growth factor-binding protein

Insulin-like growth factor-binding protein (IGFBP) is a type of protein that binds to Insulin-like growth factors (IGFs). IGFBPs are part of a larger family of proteins that regulate the actions of IGFs and have a significant role in cell growth, cell differentiation, and apoptosis.

Structure

IGFBPs are structurally characterized by the presence of an N-terminal IGF-binding domain, a C-terminal domain, and a central linker domain. The N-terminal domain is responsible for the high-affinity binding to IGFs, while the C-terminal domain is involved in binding to other proteins and extracellular matrix components.

Function

IGFBPs have several functions, including the regulation of IGF bioavailability, modulation of IGF binding to its receptors, and independent actions not related to IGFs. They can inhibit or stimulate the growth-promoting effects of IGFs on cell culture. They also have IGF-independent effects and can inhibit cell growth and induce apoptosis.

Types

There are six high-affinity IGFBPs (IGFBP-1 to IGFBP-6) that bind to IGFs with an affinity equal to or greater than that of the IGF-1 receptor. Each IGFBP has a unique pattern of expression and regulation that allows it to specifically modulate the activity of IGFs in the tissues where it is expressed.

Clinical significance

Alterations in the IGFBP system have been implicated in a variety of diseases, including cancer, diabetes, and growth disorders. For example, high levels of IGFBP-1 and IGFBP-2 have been associated with a poor prognosis in several types of cancer. In diabetes, changes in the levels of IGFBP-1 can affect insulin sensitivity and glucose metabolism.

See also

• Insulin-like growth factor 1
• Insulin-like growth factor 2
• Insulin-like growth factor 1 receptor