| Insulin-like growth factor binding protein |
||
|---|---|---|
| Identifiers | ||
| Symbol | IGFBP | |
| Pfam | PF00219 | |
| InterPro | IPR000867 | |
| SMART | SM00121 | |
| PROSITE | PDOC00194 | |
| SCOP | 1boe | |
| Available PDB structures: | ||
The Insulin-like growth factor binding protein also known as IGFBP serves as a carrier protein for Insulin-like growth factor 1 (IGF-1).[1]
Contents |
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 24 to 45 kDa proteins. 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.[2]
The IGFBPs help to lengthen the half-life of circulating IGFs in all tissues, including the prostate.[3] 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 glycoslyation and phophorylation differences.[4] 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:
References
- ^ Hwa V, Oh Y, Rosenfeld RG (December 1999). "The insulin-like growth factor-binding protein (IGFBP) superfamily". Endocr. Rev. 20 (6): 761–87. PMID 10605625.
- ^ Clemmons DR, Busby WH, Arai T, Nam TJ, Clarke JB, Jones JI, Ankrapp DK (1995). "Role of insulin-like growth factor binding proteins in the control of IGF actions". Prog. Growth Factor Res. 6 (2-4): 357–66. PMID 8817679.
- ^ Stewart CE, Bates PC, Calder TA, Woodall SM, Pell JM (September 1993). "Potentiation of insulin-like growth factor-I (IGF-I) activity by an antibody: supportive evidence for enhancement of IGF-I bioavailability in vivo by IGF binding proteins". Endocrinology 133 (3): 1462–5. PMID 7689959.
- ^ Gregory CW, DeGeorges A, Sikes RA (2001). "The IGF axis in the development and progression of prostate cancer". Recent Research Developments in Cancer: 437-462. ISBN 81-7895-002-2.
External links
 |
This biochemistry article is a stub. You can help Wikipedia by expanding it. |
|
|||||||||||||||||
This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)
