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Background
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Ubiquitin is covalently attached to target proteins by a multienzymatic system consisting of E1 (ubiquitin-activating), E2 (ubiquitin-conjugating), and E3 (ubiquitin-ligating) enzymes. NEDD8, a ubiquitin-like protein, is conjugated to proteins in a manner analogous to ubiquitinylation. beta-amyloid precursor protein-binding protein-1 (APPBP1) can bind to NEDD8 in rabbit reticulocyte lysates. However, since APPBP1 shows similarity to only the N-terminal domain of an E1 enzyme, it must interact with a protein showing similarity to the C-terminal region of E1s. By searching sequence databases, a cDNAs encoding UBA3 was identified as the human homolog of yeast Uba3. The predicted 442-amino acid UBA3 protein shares 43% sequence identity with yeast Uba3. In vitro, UBA3 formed a complex with APPBP1 and a thioester linkage with NEDD8. APPBP1/UBA3 complex may function as an E1-like enzyme for the activation of NEDD8.
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Background
References
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- Desterro, J.M., et al., J. Biol. Chem. 274(15):10618-10624 (1999).
- Gong, L., et al., FEBS Lett. 448(1):185-189 (1999).
- Okuma, T., et al., Biochem. Biophys. Res. Commun. 254(3):693-698 (1999).
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