dictyNews Volume 33 Number 12

Published in

· 10 months ago

dictyNews 
Electronic Edition 
Volume 33, number 12 
November 6, 2009 

Please submit abstracts of your papers as soon as they have been 
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or by using the form at 
http://dictybase.org/db/cgi-bin/dictyBase/abstract_submit. 

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========= 
Abstracts 
========= 

 
The Galpha4 G protein subunit interacts with the MAP kinase ERK2 using  
a D-motif that regulates developmental morphogenesis in Dictyostelium 

Hoai-Nghia Nguyen and Jeffrey A. Hadwiger* 
Department of Microbiology and Molecular Genetics, Oklahoma State University 

 
Developmental Biology, in press 

G protein Galpha subunits contribute to the specificity of different signal  
transduction pathways in Dictyostelium discoideum but Ga subunit-effector  
interactions have not been previously identified. The requirement of the  
Dictyostelium Galpha4 subunit for MAP kinase (MAPK) activation and the  
identification of a putative MAPK docking site (D-motif) in this subunit  
suggested a possible interaction between the Galpha4 subunit and MAPKs.  
In vivo association of the Galpha4 subunit and ERK2 was demonstrated by  
pull-down and co-immunoprecipitation assays.  Alteration of the D-motif  
reduced Galpha4 subunit-ERK2 interactions but only slightly altered MAPK  
activation in response to folate. Expression of the Galpha4 subunit with the  
altered D-motif in Galpha4- cells allowed for slug formation but not the  
morphogenesis associated with culmination. Expression of this mutant  
Galpha4 subunit was sufficient to rescue chemotactic movement to folate.  
Alteration of the D-motif also reduced the aggregation defect associated  
with constitutively active Galpha4 subunits. These results suggest Galpha4 
subunit-MAPK interactions are necessary for developmental morphogenesis  
but not for chemotaxis to folate. 

 
Submitted by Jeff Hadwiger [jeff.hadwiger@okstate.edu] 
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[End dictyNews, volume 33, number 12]