dictyNews Volume 40 Number 12

Published in

· 1 year ago

dictyNews 
Electronic Edition 
Volume 40, number 12 
May 2, 2014 

Please submit abstracts of your papers as soon as they have been 
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========= 
Abstracts 
========= 

 
Xiong Liu, Shi Shu, Shuhua Yu, Duck-Yeon Lee, Grzegorz Piszczek, Marjan Gucek,  
Guanghui Wang and Edward D. Korn 

Biochemical and biological properties of cortexillin III, a component of  
Dictyostelium DGAP1-cortexillin complexes 

 
Molecular Biology of the Cell, accepted 

Cortexillins I, II and III are members of the alpha-actinin/spectrin sub-family  
of Dictyostelium calponin homology proteins.  Unlike recombinant cortexillins  
I and II, which form homodimers as well as heterodimers in vitro, we find that  
recombinant cortexillin III is an unstable monomer but forms more stable  
heterodimers when co-expressed in E. coli with cortexillin I or II.  Expressed  
cortexillin III also forms heterodimers with both cortexillin I and II in vivo  
and the heterodimers complex in vivo with DGAP1, a Dictyostelium GAP protein.   
Binding of cortexillin III to DGAP1 requires the presence of either cortexillin  
I or II, i.e. cortexillin III binds to DGAP1 only as a heterodimer, and the  
heterodimers form in vivo in the absence of DGAP1.  Expressed cortexillin III  
co-localizes with cortexillins I and II in the cortex of vegetative amoebae, the  
leading edge of motile cells and the cleavage furrow of dividing cells.   
Co-localization of ctxIII and F-actin may require the heterodimer/DGAP1 complex.   
Functionally, cortexillin III may be a negative regulator of cell growth,  
cytokinesis, pinocytosis and phagocytosis as all are enhanced in cortexillin  
III-null cells. 

 
Submitted by Edward D. Korn [edk@nih.gov] 
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[End dictyNews, volume 40, number 12]