Seven IGFBPs has been described to modulate the IGF activity. IGFBPs transport IGFs, in which they may inhibit mitogenesis, differentiation, survival, and other IGF-stimulated events. IGFBPs structurally are characterized by three domains: the amino-terminal, the carboxyl-terminal, and an intermediate variable L-domain. Members of the IGFBP family exhibit 67–70% structural homology. The greatest homology among the IGFBPs is in the N- and C-terminal regions. Some IGFBPs bind to the extracellular matrix (IGFBP-2, -3, -5, and -6). In fact, a heparin-binding domain (HBD) has been identified in the C-terminal region of these binding proteins. IGFBP-1 possesses an RGD sequence, close to the C terminal, that allows the binding protein to attach to cells and to potentiate the biologic actions of IGF I. IGFBP-1 is expressed during mouse development and has a unique pattern of expression. IGFBP-1 mRNA is expressed by the liver throughout mid and late gestation. During the adult life, IGFBP-1 is a critical hepatic survival factor because it reduces the level of pro-apoptotic signals. The transcription factor related transcriptional enhancer factor-1 (RTEF-1) promotes insulin sensitivity by its expression in endothelial cells. RTEF-1 directly regulates the expression of IGFBP-1 in endothelial cells by its binding to an insulin response element on the IGFBP-1 promoter. RTEF-1 augments IGFBP-1 expression, and this increase is associated with improved systemic insulin sensitivity. Low levels of IGFBP-1 are associated with metabolic syndrome, insulin resistance, cardiovascular diseases, and cardiovascular disease associated mortality in older adults. Hyperinsulinemia decreases the levels of IGFBP-1 in the serum in normal individuals and in diabetic patients. In addition, it has been suggested that IGFBP-1 may be a marker for prognosis of patients with hepatocellular carcinoma (HCC), since IGFBP-1 inhibits the invasion and metastasis of HCC cells.
Size
25 μg
Concentration
n/a
Applications
BA
Other Names
IBP1, Placental protein 12, amniotic fluid binding protein (AFBP), IGF-BP25, IGF-BP-26, IGF-BP28, IGFBP1