Sci. STKE, 5 July 2005
BIOCHEMISTRY Variation on a Theme
Ubiquitination is a protein modification used by eukaryotic cells to regulate a broad range of cellular functions. So far, E3-ubiquitin ligases have only been known to catalyze the formation of an isopeptide bond between ubiquitin and a lysine (or the N terminus) of the substrate. Cadwell and Coscoy show that MIR1, a virally encoded E3-ubiquitin ligase, promotes ubiquitination of its substrate by a novel and unexpected mechanism. Ubiquitination of major histocompatibility complex class I (MHC-I) molecules by MIR1 does not involve an isopeptide bond but rather a thiol-ester bond at a unique cysteine residue encoded within the MHC-I intracytoplasmic domain. This finding broadens the range of candidate substrates for a potentially reversible form of ubiquitination.
Citation: Variation on a Theme. Sci. STKE 2005, tw246 (2005).
Science Signaling. ISSN 1937-9145 (online), 1945-0877 (print). Pre-2008: Science's STKE. ISSN 1525-8882