The SH3, HOOK and guanylate kinase-like domains of hDLG are important for its cytoplasmic localization

Background: hDLG, the human homologue of the Drosophila tumour suppressor dlg , functions as a scaffolding protein that facilitates the transmission of diverse downstream signals. hDLG possesses multiple protein-binding domains, including three PDZ domains, an SH3 domain, a HOOK domain and a guanylate kinase-like (GK) domain. Results: We studied the significance of the PDZ, SH3, HOOK and GK domains in the cytoplasmic localization of hDLG. We found that mutation of the SH3 or GK domain, but not the PDZ domain, resulted in a re-localization of hDLG to the nucleus. Furthermore, hDLG was found to possess a potential nuclear localization signal in the HOOK domain. Conclusion: These results suggest that the SH3, HOOK and GK domains of hDLG are important for its cytoplasmic localization.