The NH2-terminal domain of Golgin-160 contains both Golgi and nuclear targeting information.
Golgin-160 is a member of the golgin family of Golgi-localized membrane proteins. The COOH-terminal two-thirds of golgin-160 is predicted to form a coiled-coil, with an NH(2)-terminal "head" domain. To identify the Golgi targeting information in golgin-160, full-length and deletion constructs tagged with green fluorescent protein were generated. The head domain alone was targeted to the Golgi complex in the absence of assembly with endogenous golgin-160. Further truncations from both ends of the head domain narrowed the Golgi targeting information to 85 amino acids between residues 172 and 257. Surprisingly, certain truncations of the head domain also specifically accumulated in the nucleus. Both a nuclear localization signal (masked in the full-length protein) and information for nuclear retention contributed to the nuclear localization of these truncations. Because the golgin-160 head is cleaved by caspases during apoptosis, we examined the localization of epitope-tagged proteins corresponding to all potential caspase cleavage fragments. Our data suggest that three of six fragments could be targeted to the nucleus, provided that they are released from Golgi membranes after cleavage. The finding that both Golgi and nuclear targeting information is present in the same region of golgin-160 suggests that this protein may have more than one function.
Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
Stuart W
SW
Hicks
Carolyn E
CE
Machamer
D021581:Active Transport, Cell Nucleus; D000595:Amino Acid Sequence; D017209:Apoptosis; D001324:Autoantigens; D001483:Base Sequence; D020126:Brefeldin A / Q000494:pharmacology; D002467:Cell Nucleus / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D000939:Epitopes / Q000737:chemistry; D019084:Fluorescent Antibody Technique, Indirect; D006056:Golgi Apparatus / Q000378:metabolism*; D000077614:Golgi Matrix Proteins; D049452:Green Fluorescent Proteins; D006367:HeLa Cells; D006801:Humans; D008164:Luminescent Proteins / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry*; D008957:Models, Genetic; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D019913:Nuclear Localization Signals; D011233:Precipitin Tests; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D013997:Time Factors; D014162:Transfection
D001324:Autoantigens; D018076:DNA, Complementary; D000939:Epitopes; C108388:GOLGA3 protein, human; D000077614:Golgi Matrix Proteins; D008164:Luminescent Proteins; D008565:Membrane Proteins; D019913:Nuclear Localization Signals; D049452:Green Fluorescent Proteins; D020126:Brefeldin A