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© The Rockefeller University Press,
0021-9525/2001//923 $5.00
The Journal of Cell Biology, Volume 152, Number 5,
, 2001 923-934
Original Article |
The Golgi-Associated Hook3 Protein Is a Member of a Novel Family of Microtubule-Binding Proteins
kramer{at}utsw.swmed.edu
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 NH2-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.
Key Words: membrane trafficking Hook protein endosomes brefeldin A Golgi complex
© 2001 The Rockefeller University Press
Abbreviations used in this paper: aa, amino acids; BfA, Brefeldin A; CLIP, cytoplasmic linker protein; dHK, Drosophila Hook protein; hHK1, human Hook1 protein; hHK2, human Hook2 protein; hHK3, human Hook3 protein; MTOC, microtubule organizing center; MVB, multivesicular body; NZ, nocodazole; RT, room temperature.
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