Insulin-like growth factor binding protein
Encyclopedia
The Insulin-like growth factor-binding protein also known as IGFBP serves as a carrier protein
for Insulin-like growth factor 1
(IGF-1).
IGF binding proteins (IGFBPs) are proteins of 24 to 45 kDa. All six IGFBPs share 50% homology with each other and have binding affinities for IGF-I and IGF-II at the same order of magnitude as the ligands have for the IGF-IR.
The IGFBPs help to lengthen the half-life of circulating IGFs in all tissues, including the prostate. Individual IGFBPs may act to enhance or attenuate IGF signaling depending on their physiological context (i.e. cell type). Even with these similarities, some characteristics are different: chromosomal location, heparin binding domains, RGD recognition site, preference for binding IGF-I or IGF-II, and glycosylation and phophorylation differences. These structural differences can have a tremendous impact on how the IGFBPs interact with cellular basement membranes.
Carrier protein
Carrier proteins are proteins involved in the movement of ions, small molecules, or macromolecules, such as another protein, across a biological membrane. Carrier proteins are integral membrane proteins; that is they exist within and span the membrane across which they transport substances. The...
for Insulin-like growth factor 1
Insulin-like growth factor 1
Insulin-like growth factor 1 also known as somatomedin C is a protein that in humans is encoded by the IGF1 gene. IGF-1 has also been referred to as a "sulfation factor" and its effects were termed "nonsuppressible insulin-like activity" in the 1970s.IGF-1 is a hormone similar in molecular...
(IGF-1).
Function
Approximately 98% of IGF-1 is always bound to one of 6 binding proteins (IGF-BP). IGFBP-3, the most abundant protein, accounts for 80% of all IGF binding. IGF-1 binds to IGFBP-3 in a 1:1 molar ratio. IGF-BP also binds to IGF-1 inside the liver, allowing growth hormone to continuously act upon the liver to produce more IGF-1. This is important because proliferating IGF-1 + IGF-BP complex allow growth of the femur and the muscle.IGF binding proteins (IGFBPs) are proteins of 24 to 45 kDa. All six IGFBPs share 50% homology with each other and have binding affinities for IGF-I and IGF-II at the same order of magnitude as the ligands have for the IGF-IR.
The IGFBPs help to lengthen the half-life of circulating IGFs in all tissues, including the prostate. Individual IGFBPs may act to enhance or attenuate IGF signaling depending on their physiological context (i.e. cell type). Even with these similarities, some characteristics are different: chromosomal location, heparin binding domains, RGD recognition site, preference for binding IGF-I or IGF-II, and glycosylation and phophorylation differences. These structural differences can have a tremendous impact on how the IGFBPs interact with cellular basement membranes.
Family members
In humans, IGFBPs are transcribed from the following seven genes:- IGFBP1IGFBP1Insulin-like growth factor-binding protein 1 also known as placental protein 12 is a protein that in humans is encoded by the IGFBP1 gene.- Function :...
- IGFBP2IGFBP2Insulin-like growth factor-binding protein 2 is a protein that in humans is encoded by the IGFBP2 gene.-Further reading:...
- IGFBP3IGFBP3Insulin-like growth factor-binding protein 3, also known as IGFBP3, is a protein that, in humans, is encoded by the IGFBP3 gene.- Function :...
- IGFBP4IGFBP4Insulin-like growth factor-binding protein 4 is a protein that in humans is encoded by the IGFBP4 gene.IGFBP-4 is a unique protein and it consistently inhibits several cancer cells in vivo and in vitro. Its inhibitory action has been shown in vivo in prostate and colon. It is secreted by all colon...
- IGFBP5IGFBP5Insulin-like growth factor-binding protein 5 is a protein that in humans is encoded by the IGFBP5 gene.-Further reading:...
- IGFBP6IGFBP6Insulin-like growth factor-binding protein 6 is a protein that in humans is encoded by the IGFBP6 gene.-Further reading:...
- IGFBP7IGFBP7Insulin-like growth factor-binding protein 7 is a protein that in humans is encoded by the IGFBP7 gene. The major function of the protein is the regulation of availability of insulin-like growth factors in tissue as well as in modulating IGF binding to its receptors. IGFBP7 binds to IGF with high...