I think it's the horns.
From Contact Music dot com:
Mark Ronson feat. Alex Greenwald
March 13th 2006
One of the great Radiohead tracks and drummer Phil Selway's favourite song on "The Bends", "Just" combines self-loathing lyrics, a particular viscous guitar riff and middle-eight to die for. For his cover Mark Ronson not only enlisted the help of the formidable Daptones horn section (The Dap Kings) but Alex Greenwald, the lead singer of Phantom Planet (best known for "California", the theme to "The OC"). A dynamite combination of snappy horns and dusty drum breaks, "Just" belongs to the cover canon of Quantic Soul Orchestra's "Get a Move On", Alice Russell's "Seven Nation Army" and the Daptone's own "What (Have You Done For Me Lately". The man behind "Just" is one of the most sought after DJs in the world and, as one half of AllIDo Records, Ronson is currently working with Chicago rapper Rhymefest, Australian soul singer Daniel Merryweather and fabulous pop goddess Christina Aguilera. His cover of "Just" won early support from Gilles Peterson, Zane Lowe and Jo Whiley on Radio One as well as Eddy Temple-Morris on XFM, making this one of the most exciting BBE releases in years.