The GM130 and GRASP65 Golgi proteins cycle through and define a subdomain of the intermediate compartment.
Integrating the pleomorphic membranes of the intermediate compartment (IC) into the array of Golgi cisternae is a crucial step in membrane transport, but it is poorly understood. To gain insight into this step, we investigated the dynamics by which cis-Golgi matrix proteins such as GM130 and GRASP65 associate with, and incorporate, incoming IC elements. We found that GM130 and GRASP65 cycle via membranous tubules between the Golgi complex and a constellation of mobile structures that we call late IC stations. These stations are intermediate between the IC and the cis-Golgi in terms of composition, and they receive cargo from earlier IC elements and deliver it to the Golgi complex. Late IC elements are transient in nature and sensitive to fixatives; they are seen in only a fraction of fixed cells, whereas they are always visible in living cells. Finally, late IC stations undergo homotypic fusion and establish tubular connections between themselves and the Golgi. Overall, these features indicate that late IC stations mediate the transition between IC elements and the cis-Golgi face.
Marra
P
P
Department of Cell Biology and Oncology, Istituto di Ricerche Farmacologiche Mario Negri, Consorzio Mario Negri Sud, 66030 Santa Maria Imbaro (Chieti), Italy.
Maffucci
T
T
Daniele
T
T
Tullio
G D
GD
Ikehara
Y
Y
Chan
E K
EK
Luini
A
A
Beznoussenko
G
G
Mironov
A
A
De Matteis
M A
MA
D000818:Animals; D001324:Autoantigens; D019556:COS Cells; D002451:Cell Compartmentation / Q000502:physiology*; D006056:Golgi Apparatus / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D000077614:Golgi Matrix Proteins; D049452:Green Fluorescent Proteins; D007202:Indicators and Reagents / Q000378:metabolism; D008164:Luminescent Proteins / Q000235:genetics; D008562:Membrane Glycoproteins; D008565:Membrane Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data; D021381:Protein Transport / Q000502:physiology; D022142:Secretory Vesicles / Q000737:chemistry / Q000378:metabolism; D014162:Transfection; D014759:Viral Envelope Proteins / Q000378:metabolism
D001324:Autoantigens; C028391:G protein, vesicular stomatitis virus; C108705:GORASP1 protein, human; D000077614:Golgi Matrix Proteins; C097741:Golgin subfamily A member 2; D007202:Indicators and Reagents; D008164:Luminescent Proteins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D014759:Viral Envelope Proteins; D049452:Green Fluorescent Proteins