Role of xklp3, a subunit of the Xenopus kinesin II heterotrimeric complex, in membrane transport between the endoplasmic reticulum and the Golgi apparatus.
The function of the Golgi apparatus is to modify proteins and lipids synthesized in the ER and sort them to their final destination. The steady-state size and function of the Golgi apparatus is maintained through the recycling of some components back to the ER. Several lines of evidence indicate that the spatial segregation between the ER and the Golgi apparatus as well as trafficking between these two compartments require both microtubules and motors. We have cloned and characterized a new Xenopus kinesin like protein, Xklp3, a subunit of the heterotrimeric Kinesin II. By immunofluorescence it is found in the Golgi region. A more detailed analysis by EM shows that it is associated with a subset of membranes that contain the KDEL receptor and are localized between the ER and Golgi apparatus. An association of Xklp3 with the recycling compartment is further supported by a biochemical analysis and the behavior of Xklp3 in BFA-treated cells. The function of Xklp3 was analyzed by transfecting cells with a dominant-negative form lacking the motor domain. In these cells, the normal delivery of newly synthesized proteins to the Golgi apparatus is blocked. Taken together, these results indicate that Xklp3 is involved in the transport of tubular-vesicular elements between the ER and the Golgi apparatus.
Le Bot
N
N
Cell Biology and Biophysics Program, European Molecular Biological Laboratory, D-69117 Heidelberg, Germany.
Antony
C
C
White
J
J
Karsenti
E
E
Vernos
I
I
D000595:Amino Acid Sequence; D000818:Animals; D002135:Calcium-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D002460:Cell Line; D004721:Endoplasmic Reticulum / Q000502:physiology*; D006056:Golgi Apparatus / Q000502:physiology*; D049452:Green Fluorescent Proteins; D016547:Kinesins / Q000502:physiology*; D008164:Luminescent Proteins / Q000378:metabolism; D046911:Macromolecular Substances; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data; D009124:Muscle Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D009865:Oocytes / Q000502:physiology; D016133:Polymerase Chain Reaction; D018000:Receptors, Peptide / Q000737:chemistry / Q000502:physiology; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D014162:Transfection; D014981:Xenopus; D029867:Xenopus Proteins
D002135:Calcium-Binding Proteins; C064459:KDEL receptor; D008164:Luminescent Proteins; D046911:Macromolecular Substances; D009124:Muscle Proteins; D018000:Receptors, Peptide; D011993:Recombinant Fusion Proteins; C499376:XKLP3 protein, Xenopus; D029867:Xenopus Proteins; C074152:kinesin-II; D049452:Green Fluorescent Proteins; D016547:Kinesins