Identification and Characterization of a Novel Golgi Protein, Golgin-67

In the course of screening a λgt11 human leukemic T-cell cDNA expression library with an antibody specific to the mitotic target of Src, Sam68, we identified and cloned a cDNA encoding a novel protein with a predicted molecular mass of 51.4 kDa. Polyclonal antibodies raised to a His6-tagged construct of this protein, detected a ∼67-kDa protein in immunoprecipitation experiments, and cytological studies showed that this protein localized to the Golgi complex, through colocalization experiments with specific Golgi markers. Therefore, we designated this protein golgin-67. Sequence analysis revealed that golgin-67 is a highly coiled-coil protein, with potential Cdc2 and Src kinase phosphorylation motifs. It has sequence homologies to other Golgi proteins, including the coatamer complex I vesicle docking protein, GM130. Structurally, golgin-67 resembles, golgin-84, an integral membrane Golgi protein with an N-terminal coiled-coil domain and a single C-terminal transmembrane domain. The C-terminal region of golgin-67, which contains a predicted transmembrane domain, was demonstrated to be essential for its Golgi localization.