The Putative Tumor Suppressor TESTIN Changes Its Conformational States In Different Cellular Compartments

The human TESTIN gene which encodes a protein TES with 421 amino acids is a putative tumor suppressor and is located at 7q 31.1/2 within fragile chromosomal region and localizes to the cytoplasm as a component of focal adhesions and cell contacts.TES contains a PET domain in the NH2-terminus and three tandem LIM domains in the COOH-terminus.It has been hypothesized that interactions between two termini of TES might lead to a "closed" conformational state of the protein.Here,we provide evidence for different conformational states of TES.We confirmed that the NH2-terminus of TES can interact with its third LIM domain in the COOH-terminus by GST pull-down assays.In addition,antisera against the full-length or two truncations of TES were prepared to examine the relationship between the conformation and cellular distribution of the protein,further study shows that TES could interact with AP-2α,Overexpressing TES accelerates the degradation of AP-2αthrough the proteasome pathway and suppresses the transactivity of AP-2α.We found that these antisera recognize different regions of TES and showed that TES is co-localised with the marker protein B23 in nucleolus,in addition to its localization in endoplasmic reticulum(ER). Furthermore,our co-immunoprecipitation(co-IP) analysis of TES and B23 demonstrated their co-existence in the same complex.Taken together, our results suggest that TES has different conformational states in different cellular compartments,and a "closed" conformational state of TES may be involved in nucleolar localization.Changes of conformational state of TES help TES involve in important cell procedures.