Please use this identifier to cite or link to this item:
|Title:||Cell adhesion molecule DdCAD-1 is imported into contractile vacuoles by membrane invagination in a Ca2- and conformation-dependent manner|
|Citation:||Sriskanthadevan, S., Lee, T., Lin, Z., Yang, D., Siu, C.-H. (2009-12-25). Cell adhesion molecule DdCAD-1 is imported into contractile vacuoles by membrane invagination in a Ca2- and conformation-dependent manner. Journal of Biological Chemistry 284 (52) : 36377-36386. ScholarBank@NUS Repository. https://doi.org/10.1074/jbc.M109.057257|
|Abstract:||The cadA gene in Dictyostelium encodes a Ca2+-dependent cell adhesion molecule DdCAD-1 that contains two β-sandwich domains. DdCAD-1 is synthesized in the cytoplasm as a soluble protein and then transported by contractile vacuoles to the plasma membrane for surface presentation or secretion. DdCAD-1-green fluorescent protein (GFP) fusion protein was expressed in cadA-null cells for further investigation of this unconventional protein transport pathway. Both morphological and biochemical characterizations showed that DdCAD-1-GFP was imported into contractile vacuoles. Time-lapse microscopy of transfectants revealed the transient appearance of DdCAD-1-GFP-filled vesicular structures in the lumen of contractile vacuoles, suggesting that DdCAD-1 could be imported by invagination of contractile vacuole membrane. To assess the structural requirements in this transport process, the N-terminal and C-terminal domains of DdCAD-1 were expressed separately in cells as GFP fusion proteins. Both fusion proteins failed to enter the contractile vacuole, suggesting that the integrity of DdCAD-1 is required for import. Such a requirement was also observed in in vitro reconstitution assays using His6-tagged fusion proteins and purified contractile vacuoles. Import of DdCAD-1 was compromised when two of its three Ca2+-binding sites were mutated, indicating a role for Ca2+ in the import process. Spectral analysis showed that mutations in the Ca2+-binding sites resulted in subtle conformational changes. Indeed, proteins with altered conformation failed to enter the contractile vacuole, suggesting that the import signal is somehow integrated in the three-dimensional structure of DdCAD-1. © 2009 by The American Society for Biochemistry and Molecular Biology, Inc.|
|Source Title:||Journal of Biological Chemistry|
|Appears in Collections:||Staff Publications|
Show full item record
Files in This Item:
There are no files associated with this item.
checked on Jan 16, 2019
WEB OF SCIENCETM
checked on Jan 9, 2019
checked on Nov 2, 2018
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.