Betacellulin is a protein that in humans is encoded by the BTCgene located on chromosome 4 at locus 4q13-q21. 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.
BTC is a polymer of about 62-111 amino acid residues.
Secondary Structure: 6% helical (1 helices; 3 residues) 36% beta sheet (5 strands; 18 residues)
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 (mBTC) 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 (hBTC), 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 (if you would like to see an image of what parts of the sequence code for the secondary structures observed in the image, click here). Also, a Ramachandran plot can be found here.
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