Ubiquitin-like modifier-activating enzyme 1

UBA1 (ubiquitin-like modifier-activating enzyme 1) catalyzes the essential first step of ubiquitin conjugation, adenylating ubiquitin's C-terminal glycine and transferring it to a cysteine residue within E1 itself to form a thioester intermediate (UniProt: P22314). This reaction initiates the ubiquitin-proteasome system pathway responsible for marking cellular proteins for degradation. UBA1 also plays roles in DNA damage response and repair, promoting recruitment of DNA repair factors TP53BP1 and BRCA1 at lesion sites and supporting radiation-induced focus formation.

UBA1 mutations are associated with X-linked spinal muscular atrophy type 2 (SMAX2) and VEXAS syndrome, a late-onset inflammatory disorder predominantly affecting males (UniProt: P22314). The protein's broader role in protein quality control and cellular stress responses positions it within fundamental cellular homeostasis pathways relevant to neurological function.

In Alzheimer's disease, UBA1 shows ambiguous directionality across subcellular fractions in post-mortem AD brain tissue compared to age-matched controls, with a mean log2 fold-change of 0.0225 (Chaparral AD proteomics). This near-zero average suggests minimal net change in total UBA1 levels, though differential regulation across distinct cellular compartments cannot be excluded.