UBQ3 (POLYUBIQUITIN 3); protein binding. similar to UBQ4 (ubiquitin 4), protein binding [Arabidopsis thaliana] (TAIR:AT5G20620.1); similar to polyubiquitin [Thlaspi caerulescens] (GB:AAY86773.1); contains InterPro domain Ubiquitin; (InterPro:IPR000626)