Transforming Growth Factor Alpha

Transforming growth factor alpha (TGF alpha) is a small 50 amino acid residue long mitogenic protein that contains three disulfide bridges. TGF alpha shares about 30% sequence identity with epidermal growth factor (EGF) and competes with EGF for the same membrane-bound receptor sites. High amounts of TGF alpha/EGF receptor complexes have been noticed in some human cancers. TGF alphas are secreted by human cancer cells and retrovirus-transformed fibroblasts. TGF alpha acts alongside other growth factors such as type-beta transforming growth factor (TGF beta) to activate phenotypic cellular changes in certain cell lines. TGF alpha and other EGF-like proteins are thought to play a role in wound healing and oncogenesis.

The picture of TGF alpha shown here is colored by secondary structure. The three disulfide bonds found in the protein are between the following residues: Cys8-Cys21, Cys16-Cys32, and Cys34-Cys43. The side chains shown are thought to play an important role in the functionality of the TGF alpha and are Phe15, Arg42, and Leu48.

Another conformer of TGF without side chains:

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