Identification of Mrj, a DnaJ/Hsp40 family protein, as a keratin 8/18 filament regulatory protein |
| |
Authors: | Izawa I Nishizawa M Ohtakara K Ohtsuka K Inada H Inagaki M |
| |
Institution: | Division of Biochemistry, Aichi Cancer Center Research Institute, Chikusa-ku, Nagoya, Aichi 464-8681, Japan. |
| |
Abstract: | To elucidate the function of keratins 8 and 18 (K8/18), major components of the intermediate filaments of simple epithelia, we searched for K8/18-binding proteins by screening a yeast two-hybrid library. We report here that human Mrj, a DnaJ/Hsp40 family protein, directly binds to K18. Among the interactions between DnaJ/Hsp40 family proteins and various intermediate filament proteins that we tested using two-hybrid methods, Mrj specifically interacted with K18. Immunostaining with anti-Mrj antibody showed that Mrj colocalized with K8/18 filaments in HeLa cells. Mrj was immunoprecipitated not only with K18, but also with the stress-induced and constitutively expressed heat shock protein Hsp/c70. Mrj bound to K18 through its C terminus and interacted with Hsp/c70 via its N terminus, which contains the J domain. Microinjection of anti-Mrj antibody resulted in the disorganization of K8/18 filaments, without effects on the organization of actin filaments and microtubules. Taken together, these results suggest that Mrj may play an important role in the regulation of K8/18 filament organization as a K18-specific co-chaperone working together with Hsp/c70. |
| |
Keywords: | |
本文献已被 PubMed 等数据库收录! |
|