|
||
© The Rockefeller University Press,
0021-9525/2001//1499 $5.00
The Journal of Cell Biology, Volume 153, Number 7,
, 2001 1499-1510
Original Article |
Cytoplasmic Dynein Regulation by Subunit Heterogeneity and Its Role in Apical Transport
chsung{at}mail.med.cornell.edu
Despite the existence of multiple subunit isoforms for the microtubule motor cytoplasmic dynein, it has not yet been directly shown that dynein complexes with different compositions exhibit different properties. The 14-kD dynein light chain Tctex-1, but not its homologue RP3, binds directly to rhodopsin's cytoplasmic COOH-terminal tail, which encodes an apical targeting determinant in polarized epithelial Madin-Darby canine kidney (MDCK) cells. We demonstrate that Tctex-1 and RP3 compete for binding to dynein intermediate chain and that overexpressed RP3 displaces endogenous Tctex-1 from dynein complexes in MDCK cells. Furthermore, replacement of Tctex-1 by RP3 selectively disrupts the translocation of rhodopsin to the MDCK apical surface. These results directly show that cytoplasmic dynein function can be regulated by its subunit composition and that cytoplasmic dynein is essential for at least one mode of apical transport in polarized epithelia.
Key Words: cytoplasmic dynein light chain Tctex-1 RP3 apical transport rhodopsin
© 2001 The Rockefeller University Press
A.W. Tai and J.-Z. Chuang contributed equally to this work.Abbreviations used in this paper: CMV, cytomegalovirus; GFP, green fluorescent protein; GST, glutathione S-transferase; HA, hemagglutinin; HC, heavy chain; IC, intermediate chain; LC, light chain; LDL, low density lipoprotein; LIC, light intermediate chain.
|
|