p24 and p23, the major transmembrane proteins of COPI-coated transport vesicles, form hetero-oligomeric complexes and cycle between the organelles of the early secretory pathway.
COPI-coated vesicles that bud off the Golgi complex contain two major transmembrane proteins, p23 and p24. We have localized the protein at the Golgi complex and at COPI-coated vesicles. Transport from the intermediate compartment (IC) to the Golgi can be blocked at 15 degrees C, and under these conditions p24 accumulates in peripheral punctated structures identified as IC. Release from the temperature block leads to a redistribution of p24 to the Golgi, showing that p24, similar to p23, cycles between the IC and Golgi complex. Immunoprecipitations of p24 from cell lysates and from detergent-solubilized Golgi membranes and COPI-coated vesicles show that p24 and p23 interact with each other to form a complex. Transient transfection of p23 in HeLa cells shows that p23 and p24 colocalize in structures induced by the overexpression of p23. Taken together p24 interacts with p23 and constitutively cycles between the organelles of the early secretory pathway.
Gommel
D
D
Biochemie-Zentrum, Heidelberg, University of Heidelberg, Germany.
Orci
L
L
Emig
E M
EM
Hannah
M J
MJ
Ravazzola
M
M
Nickel
W
W
Helms
J B
JB
Wieland
F T
FT
Sohn
K
K
D000595:Amino Acid Sequence; D000818:Animals; D001693:Biological Transport, Active; D016466:CHO Cells; D020756:Coatomer Protein; D006224:Cricetinae; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D015870:Gene Expression; D006056:Golgi Apparatus / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D046911:Macromolecular Substances; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015388:Organelles / Q000378:metabolism; D011817:Rabbits; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D014162:Transfection
D020756:Coatomer Protein; D046911:Macromolecular Substances; D008565:Membrane Proteins; C046375:NRSN1 protein, human; D011994:Recombinant Proteins