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First published online April 28, 2005

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RasGEFs show Dicty the way

Chemotactic stimuli, such as cyclic AMP in Dictyostelium, cause cells to polarize and migrate towards them. Distinguishing proteins that function at various stages in polarization and migration is essential if we are to understand chemotaxis. On p. 1899, Peter van Haastert and co-workers do just this, implicating two related nucleotide-binding proteins at different points in the process. GbpC and GbpD are recently identified proteins that each possess a cyclic-nucleotide-binding domain and a RasGEF (Ras-regulating guanine-nucleotide-exchange factor) domain. van Haastert and co-workers have generated gbpC-null and gbpD-null cells and show the mutations have opposing effects: the gbpC-null mutation inhibits chemotaxis, whereas the gbpD-null mutation promotes it. The gbpC-null mutation blocks the ability of cells to polarize effectively and mobilize myosin II motors; gbpD-null cells are by contrast hyperpolar. Indeed overexpression of GbpD inhibits chemotaxis; in this case cells form numerous pseudopodia, fail to develop a leading edge and are highly adhesive. The authors conclude that GbpC regulates polarization in response to chemoattractants by controlling myosin motors that drive the necessary cytoskeletal rearrangements. They propose that GbpD is involved in generation of substrate-attached pseudopodia, which antagonises this and allows cells to change direction.

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Related articles in JCS:

RasGEF-containing proteins GbpC and GbpD have differential effects on cell polarity and chemotaxis in Dictyostelium

Leonard Bosgraaf, Arjen Waijer, Ruchira Engel, Antonie J. W. G. Visser, Deborah Wessels, David Soll, and Peter J. M. van Haastert
JCS 2005 118: 1899-1910. [Abstract] [Full Text]  

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Related articles in JCS Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Search for Related Content Social Bookmarking                         What's this?