Characterisation of human RING finger protein TRIM69, a novel testis E3 ubiquitin ligase and its subcellular localisation

The E3 ubiquitin ligase activity and subcellular localisation of human TRIM69 (hTRIM69) gene were studied. It was found that hTRIM69 mediated ubiquitination in an E2 conjugating enzyme selective fashion in vitro and an intact RING finger domain was indispensible for the process. Further evidences showed that hTRIM69 could mediate ubiquitination in vivo, which could be enhanced by a proteasome inhibitor. hTRIM69 was found to localise in both the cytoplasm and the nucleus in a speckled aggregating pattern, which also required an intact RING finger domain. Collectively, hTRIM69 is a novel E3 ubiquitin ligase identified from human testis and may function to ubiquitinate its particular substrates during spermatogenesis.

► Isolation of a novel gene TRIM69 from a human testis subtracted cDNA library. ► Characterisation of TRIM69, a novel testis E3 ubiquitin ligase and its subcellular localisation. ► Intact RING finger motif required for TRIM69 E3 ligase activity and its subcellular localisation.