This entry represents NEDD8-activating enzyme E1 catalytic subunit from fungi, plants and invertebrates. In budding yeasts, it is also known as Uba3, which is a catalytic subunit of the dimeric Uba3-Ula1 E1 enzyme that activates NEDD8/Rub1 before neddylation, the process by which the ubiquitin-like protein NEDD8 is conjugated to its target proteins []. In C.elegans, Uba3 (also known as rfl-1) is required for cytokinesis and mitotic spindle orientation [].
This entry represents a presumed C-terminal domain of ubiquitin 3 binding proteins (But2). But2 is conserved in yeasts. It binds to Uba3 and is involved in the NEDD8 signalling pathway [].
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 []. Drosophila APP-BP1 interacts antagonistically with APPL (APP-like protein) during Drosophila development [].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 [].
