The Golgi-associated hook3 protein is a member of a novel family of microtubule-binding proteins.
Microtubules are central to the spatial organization of diverse membrane-trafficking systems. Here, we report that Hook proteins constitute a novel family of cytosolic coiled coil proteins that bind to organelles and to microtubules. The conserved NH(2)-terminal domains of Hook proteins mediate attachment to microtubules, whereas the more divergent COOH-terminal domains mediate the binding to organelles. Human Hook3 bound to Golgi membranes in vitro and was enriched in the cis-Golgi in vivo. Unlike other cis-Golgi-associated proteins, however, a large fraction of Hook3 maintained its juxtanuclear localization after Brefeldin A treatment, indicating a Golgi-independent mechanism for Hook3 localization. Because overexpression of Hook3 caused fragmentation of the Golgi complex, we propose that Hook3 participates in defining the architecture and localization of the mammalian Golgi complex.
Center for Basic Neuroscience and Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA.
J H
JH
Walenta
A J
AJ
Didier
X
X
Liu
H
H
Krämer
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D020126:Brefeldin A / Q000494:pharmacology; D002460:Cell Line; D005455:Fluorescent Antibody Technique; D006056:Golgi Apparatus / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D006801:Humans; D007425:Intracellular Membranes / Q000187:drug effects / Q000378:metabolism; D008854:Microscopy, Electron; D008869:Microtubule-Associated Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008870:Microtubules / Q000187:drug effects / Q000378:metabolism*; D008970:Molecular Weight; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D017384:Sequence Deletion / Q000235:genetics
D008869:Microtubule-Associated Proteins; C425466:hook3 protein, human; D020126:Brefeldin A