Aos1containing

Aos1containing is a descriptive term used in molecular biology to refer to proteins, enzyme complexes, or subcomplexes that include the Aos1 subunit. In eukaryotes, Aos1 is part of the SUMO-activating enzyme (SAE1/SAE2) that initiates SUMOylation by activating SUMO for subsequent transfer to target proteins.

In this context, Aos1-containing SUMO E1 enzymes form a heterodimer with Uba2 (SAE2). The Aos1 subunit primarily plays a regulatory or scaffolding role, while Uba2 contains the catalytic cysteine that forms a SUMO thioester intermediate. The activation process involves adenylation of SUMO followed by thioester bond formation with the catalytic subunit, after which SUMO is transferred to the E2 enzyme Ubc9 and ultimately to substrates, often with the assistance of E3 ligases.

Aos1-containing complexes are conserved across many eukaryotic lineages, highlighting the essential nature of SUMO activation in cellular regulation. Sumoylation influences a wide range of processes, including nuclear transport, transcriptional regulation, DNA repair, and responses to stress. Because Aos1-containing complexes underpin the first step of SUMO conjugation, they are critical for proper SUMOylation and, in many organisms, are required for viability.

In research literature, the term “Aos1-containing” is used to describe proteins or complexes that harbor the Aos1 domain or participate as part of the SUMO E1 activating enzyme. It is not a reference to a single gene product, but rather a functional descriptor for components associated with the Aos1 subunit across species.