Characterization of a cis-Golgi matrix protein, GM130.
Antisera raised to a detergent- and salt-resistant matrix fraction from rat liver Golgi stacks were used to screen an expression library from rat liver cDNA. A full-length clone was obtained encoding a protein of 130 kD (termed GM130), the COOH-terminal domain of which was highly homologous to a Golgi human auto-antigen, golgin-95 (Fritzler et al., 1993). Biochemical data showed that GM130 is a peripheral cytoplasmic protein that is tightly bound to Golgi membranes and part of a larger oligomeric complex. Predictions from the protein sequence suggest that GM130 is an extended rod-like protein with coiled-coil domains. Immunofluorescence microscopy showed partial overlap with medial- and trans-Golgi markers but almost complete overlap with the cis-Golgi network (CGN) marker, syntaxin5. Immunoelectron microscopy confirmed this location showing that most of the GM130 was located in the CGN and in one or two cisternae on the cis-side of the Golgi stack. GM130 was not re-distributed to the ER in the presence of brefeldin A but maintained its overlap with syntaxin5 and a partial overlap with the ER-Golgi intermediate compartment marker, p53. Together these results suggest that GM130 is part of a cis-Golgi matrix and has a role in maintaining cis-Golgi structure.
Nakamura
N
N
Cell Biology Laboratory, Imperial Cancer Research Fund, London, UK.
Rabouille
C
C
Watson
R
R
Nilsson
T
T
Hui
N
N
Slusarewicz
P
P
Kreis
T E
TE
Warren
G
G
D000595:Amino Acid Sequence; D000818:Animals; D001324:Autoantigens; D001483:Base Sequence; D002458:Cell Fractionation; D003001:Cloning, Molecular; D005455:Fluorescent Antibody Technique; D015723:Gene Library; D005820:Genetic Testing; D006056:Golgi Apparatus / Q000737:chemistry* / Q000235:genetics / Q000648:ultrastructure; D008099:Liver / Q000166:cytology; D008565:Membrane Proteins / Q000032:analysis / Q000737:chemistry* / Q000235:genetics* / Q000648:ultrastructure; D008969:Molecular Sequence Data; D011817:Rabbits; D051381:Rats; D017422:Sequence Analysis, DNA
D001324:Autoantigens; C097741:Golgin subfamily A member 2; D008565:Membrane Proteins