UBA6（Ubiquitin-like modifier-activating enzyme 6）是人體中由UBA6基因編碼的一種蛋白質。UBA6蛋白通過將ATP與其C端的甘氨酸殘基腺苷化，然后將這個殘基連接到E1中半胱氨酸的側鏈上，形成一個泛素-E1巰基酯和游離的AMP（腺苷二磷酸）。UBA6專一于泛素，不激活類似泛素的肽鏈。與UBE1在底物E2充電特異性上有所不同，不會充電細胞周期E2，如CDC34。UBA6對胚胎發育至關重要。它還參與UBD/FAT10的結合過程。UBA6的第二剪切異構體可能在泛素系統中起關鍵作用，影響精子發生和男性生育能力。

    Ubiquitin-like modifier-activating enzyme 6 is a protein in humans that is encoded by UBA6 gene. Activates ubiquitin by first adenylating its C-terminal glycine residue with ATP, and thereafter linking this residue to the side chain of a cysteine residue in E1, yielding a ubiquitin-E1 thioester and free AMP. Specific for ubiquitin, does not activate ubiquitin-like peptides. Differs from UBE1 in its specificity for substrate E2 charging. Does not charge cell cycle E2s, such as CDC34. Essential for embryonic development. Required for UBD/FAT10 conjugation. Isoform 2 may play a key role in ubiquitin system and may influence spermatogenesis and male fertility.