Involvement of a Golgi-resident GPI-anchored protein in maintenance of the Golgi structure
The Golgi apparatus consists of a series of flattened cisternal membranes that are aligned in parallel to form stacks. Cytosolic-oriented Golgi-associated proteins have been identified that may coordinate or maintain the Golgi architecture. Here, we describe a novel GPI-anchored protein, Golgi-resident GPI-anchored protein (GREG) that has a brefeldin A-sensitive Golgi localization. GREG resides in the Golgi lumen as a cis-oriented homodimer, due to strong interactions between coiled-coil regions in the C termini. Dimerization of GREG as well as its Golgi localization depends on a unique tandem repeat sequence within the coiled-coil region. RNA-mediated interference of GREG expression or expression of GREG mutants reveals an essential role for GREG in maintenance of the Golgi integrity. Under these conditions, secretion of the vesicular stomatitis virus glycoprotein protein as a marker for protein transport along the secretory pathway is inhibited, suggesting a loss of Golgi function as well. These results imply the involvement of a luminal protein in Golgi structure and function.
Keywords: Amino Acid Sequence ; Animals ; CHO Cells ; Cell Membrane/metabolism ; Cricetinae ; Cricetulus ; Glycosylphosphatidylinositols/metabolism ; Golgi Apparatus/*metabolism/ultrastructure ; Membrane Glycoproteins/metabolism ; Membrane Proteins/genetics/*metabolism ; Molecular Sequence Data ; Protein Transport ; Repetitive Sequences ; Amino Acid ; Sequence Homology ; Amino Acid ; Viral Envelope Proteins/metabolism ; Amino Acid
Department of Biochemistry and Cell Biology and Institute of Biomembranes, Utrecht University, 3508 TD Utrecht, The Netherlands.
Record created on 2009-01-30, modified on 2016-08-08