Betacellulin is a protein that in humans is encoded by the BTCgene located on chromosome 4 at locus 4q13-q21. Betacellulin, is a part of an Epidermal Growth Factor family that has been spotted in the conditioned cell lines that was taken from mice pancreatic Beta cell tumor. When a sequence of the purified protein and a cloned cDNA was extracted, it supported the claim that in fact betacellulin is a new ligand formed from the epidermal growth factor receptor. As the role a EGFR, betacellulin is manifested by different form of muscles and tissues, it also has a great effect of nitrogen that is used for retinal pigment epithelial cells and vascular smooth muscle cells. While many studies attest a role for betacellulin in the differentiation of pancreatic β-cells, the last decade witnessed the association of betacellulin with many additional biological processes, ranging from reproduction to the control of neural stem cells. Betacellulin is a member of the EGF family of growth factors. It is synthesized primarily as a transmembrane precursor, which is then processed to mature molecule by proteolytic events. This protein is a ligand for the EGF receptor. As a typical EGFR ligand, betacellulin is expressed by a variety of cell types and tissues, and the soluble growth factor is proteolytically cleaved from a larger membrane-anchored precursor. Betacellulin stimulated the proliferation of retinal pigment epithelial and vascular smooth muscle cells at a concentration of 30 pM but did not stimulate the growth of several other cell types, such as endothelial cells and fetal lung fibroblasts. Betacellulin chemically bonds and activates tyrosine residues phosphorylation of the epidemic growth factor. Osteoblasts, which are responsible for forming and mineralizing osteoid, express EGF receptors and alter rates of proliferation and differentiation in response to EGF receptor activation. Transgenic mice over-expressing the EGF-like ligand betacellulin exhibit increased cortical bone deposition; however, because the transgene is ubiquitously expressed in these mice, the identity of cells affected by BTC and responsible for increased cortical bone thickness remains unknown. We have therefore examined the influence of BTC upon mesenchymal stem cell and pre-osteoblast differentiation and proliferation. BTC decreases the expression of osteogenic markers in both MSCs and pre-osteoblasts increases in proliferation require hypoxia-inducible factor-alpha, as an HIF antagonist prevents BTC-driven proliferation. Both MSCs and pre-osteoblasts express EGF receptors ErbB1, ErbB2, and ErbB3, with no change in expression under osteogenic differentiation. These are the first data that demonstrate an influence of BTC upon MSCs and the first to implicate HIF-alpha in BTC-mediated proliferation. as you can see the role of Betacellulinis a bit flexible enough to divert its response based on part where it binds.
Structure
BTC is a polymer of about 62-111 amino acid residues. Secondary Structure: 6% helical 36% beta sheet
BTC was originally identified as a growth-promoting factor in mouse pancreatic β-cell carcinoma cell line and has since been identified in humans. Mouse BTC is expressed as a 178-amino acid precursor. The membrane-bound precursor is cleaved to yield mature secreted mBTC. BTC is synthesized in a wide range of adult tissues and in many cultured cells, including smooth muscle cells and epithelial cells. The amino acid sequence of mature mBTC is 82.5%, identical with that of human BTC, and both exhibit significant overall similarity with other members of the EGF family.
About the image
The structure for the small protein Betacellulin that is shown was determined by two-dimensional nuclear magnetic resonance spectroscopy. The species that BTC was taken from was Homo sapiens. This particular molecule of BTC has a formula weight of 5916.9 and its sequence was determined to be RKGHFSRCPKQYKHYCIKGRCRFVVAEQTPSCVCDEGYIGARCERVDLFY. Also, a Ramachandran plot can be found .
