GRASP55, a second mammalian GRASP protein involved in the stacking of Golgi cisternae in a cell-free system.
We have identified a 55 kDa protein, named GRASP55 (Golgi reassembly stacking protein of 55 kDa), as a component of the Golgi stacking machinery. GRASP55 is homologous to GRASP65, an N-ethylmaleimide-sensitive membrane protein required for the stacking of Golgi cisternae in a cell-free system. GRASP65 exists in a complex with the vesicle docking protein receptor GM130 to which it binds directly, and the membrane tethering protein p115, which also functions in the stacking of Golgi cisternae. GRASP55 binding to GM130, could not be detected using biochemical methods, although a weak interaction was detected with the yeast two-hybrid system. Cryo-electron microscopy revealed that GRASP65, like GM130, is present on the cis-Golgi, while GRASP55 is on the medial-Golgi. Recombinant GRASP55 and antibodies to the protein block the stacking of Golgi cisternae, which is similar to the observations made for GRASP65. These results demonstrate that GRASP55 and GRASP65 function in the stacking of Golgi cisternae.
Shorter
J
J
Cell Biology Laboratory, Imperial Cancer Research Fund, 44 Lincoln's Inn Fields, London WC2A 3PX.
Watson
R
R
Giannakou
M E
ME
Clarke
M
M
Warren
G
G
Barr
F A
FA
D000595:Amino Acid Sequence; D000818:Animals; D001324:Autoantigens; D001483:Base Sequence; D002474:Cell-Free System; D003001:Cloning, Molecular; D020285:Cryoelectron Microscopy; D017931:DNA Primers / Q000235:genetics; D006056:Golgi Apparatus / Q000378:metabolism* / Q000648:ultrastructure; D000077614:Golgi Matrix Proteins; D006367:HeLa Cells; D006801:Humans; D066298:In Vitro Techniques; D046911:Macromolecular Substances; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D011485:Protein Binding; D051381:Rats; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
D001324:Autoantigens; D017931:DNA Primers; C108705:GORASP1 protein, human; C122048:GORASP2 protein, human; D000077614:Golgi Matrix Proteins; C097741:Golgin subfamily A member 2; C491577:Gorasp1 protein, rat; D046911:Macromolecular Substances; D008565:Membrane Proteins; D011994:Recombinant Proteins