InterPro domain: IPR030667

APP-BP1 (beta-Amyloid precursor protein binding protein 1), also known as Ula1 in yeasts, is a regulatory subunit of the E1 enzyme. Human APP-BP1 is necessary for cell cycle progression through the S-M checkpoint [ 1 ]. Drosophila APP-BP1 interacts antagonistically with APPL (APP-like protein) during Drosophila development [ 2 ].

Ubiquitin-like proteins (ublps) are conjugated to their targets by the sequential action of E1, E2 and often E3 enzymes. Each Ublp has a dedicated E1, or activating enzyme, that initiates its conjugation cascade. In humans the NEDD8 activating E1 enzyme is a heterodimer composed of APP-BP1 and UBA3 subunits. The ubiquitin-like protein (Ublp) NEDD8 regulates cell division, signalling and embryogenesis [ 3 ].

1. The amyloid precursor protein-binding protein APP-BP1 drives the cell cycle through the S-M checkpoint and causes apoptosis in neurons. J. Biol. Chem. 275, 8929-35
2. Drosophila homolog of APP-BP1 (dAPP-BP1) interacts antagonistically with APPL during Drosophila development. Cell Death Differ. 14, 103-15
3. Insights into the ubiquitin transfer cascade from the structure of the activating enzyme for NEDD8. Nature 422, 330-4