EVI5 is a novel centrosomal protein that binds to α- and γ-tubulin

The human EVI5 protein carries a TBC domain indicative of Rab GTPase activating protein (GAP) activity, and an extensive coiled-coil motif in the C-terminal region. EVI5 is ubiquitously expressed in adult, fetal, and cancer tissues and exists as two mRNA species resulting from differential use of polyadenylation signals. Western blot analysis suggests that different molecular weight protein species are probably generated by posttranslational modification. FPLC analysis demonstrates that EVI5 protein can form dimers and confocal microscopy indicates that EVI5, in addition to a diffuse localization in the nucleus, also preferentially localizes to the pericentriolar material in interphase cells. Immunoprecipitation and GST pull-down experiments demonstrate that EVI5 exists in complexes with both α- and γ-tubulin. Both interactions are localized to the N-terminal part of the EVI5 protein. Thus, EVI5 is a novel centrosomal protein with a complex expression pattern and subcellular localization, possibly involved in centrosome stability and dynamics.