DeMartino George N
Department of Physiology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9040, USA.
Trends Biochem Sci. 2009 Apr;34(4):155-8. doi: 10.1016/j.tibs.2008.12.005. Epub 2009 Mar 11.
Most eukaryotic proteins are degraded by the 26S proteasome as a consequence of their covalent modification with ubiquitin. Although the proteasome is found in some prokaryotes, ubiquitin is not, which indicates that substrates are targeted to prokaryotic proteasomes by a fundamentally different mechanism. A recent study has identified Pup (prokaryotic ubiquitin-like protein) as a mycobacterial protein that functions in a manner analogous to ubiquitin for proteasome-dependent proteolysis in prokaryotes.
大多数真核生物蛋白质会因被泛素共价修饰而被26S蛋白酶体降解。虽然在一些原核生物中也发现了蛋白酶体，但泛素却没有，这表明底物通过一种根本不同的机制靶向原核生物蛋白酶体。最近一项研究已鉴定出Pup（原核生物类泛素蛋白）是一种分枝杆菌蛋白，其作用方式类似于泛素，用于原核生物中蛋白酶体依赖性蛋白水解。
