Characterization of nuclear localization and nuclear export signals of yeast actin-binding protein Pan1

Pan1 is an actin patch-associated protein involved in endocytosis. Our studies revealed that in oleate-grown cells Pan1 is located in the nucleus as well as in patches. One of three putative nuclear localization signals (NLS) of Pan1, NLS2, directed β-galactosidase (β-gal) to the nucleus. However, GFP-Pan1886−1219, containing NLS2, was found in the cytoplasm indicating that it may contain a nuclear export signal (NES). A putative Pan1 NES, overlapping with NLS3, re-addressed NLSH2B-NES/NLS3-β-gal from the nucleus to the cytoplasm. Inactivation of the NES allowed NLS3 to be effective. Thus, Pan1 contains functional NLSs and a NES and appears to shuttle in certain circumstances.