Universität zu Köln

Omosigho, Napoleon Nosa (2014). The Dictyostelium discoideum RACK1 orthologue has roles in growth and development. PhD thesis, Universität zu Köln.

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Abstract

The receptor for activated C-kinase 1 (RACK1) is a conserved protein belonging to the WD40 repeat family of proteins. It folds into a beta propeller with seven blades which allow interactions with many proteins. Thus it can serve as a scaffolding protein and have roles in several cellular processes. We identified the product of the Dictyostelium discoideum gpbB gene as the Dictyostelium RACK1 homolog. The protein is mainly cytosolic but can also associate with cellular membranes. DdRACK1 binds to phosphoinositides (PIPs) in protein-lipid overlay and liposomes-binding assays. The basis of this activity resides in a basic region located in the extended loop between blades 6 and 7 as revealed by mutational analysis. Similar to RACK1 proteins from other organisms DdRACK1 interacts with G protein subunits alpha, beta and gamma as shown by yeast two-hybrid, pulldown, and immunoprecipitation assays. Unlike the Saccharomyces cerevisiae and Cryptococcus neoformans RACK1 proteins it does not appear to take over Gβ function in D. discoideum as developmental and other defects were not rescued in Gβ null mutants overexpressing GFP-DdRACK1. Overexpression of GFP-tagged DdRACK1 and a mutant version (DdRACK1mut) which carried a charge-reversal mutation in the basic region in wild type cells led to changes during growth and development. DdRACK1 interacts with heterotrimeric G proteins and can through these interactions impact on processes specifically regulated by these proteins.

Item Type:	Thesis (PhD thesis)
Creators:	Creators Email ORCID ORCID Put Code Omosigho, Napoleon Nosa napnices@yahoo.com UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-56341
Date:	6 May 2014
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Medicine > Biochemie > Institut I für Biochemie
Subjects:	Natural sciences and mathematics Life sciences
Uncontrolled Keywords:	Keywords Language Dictyostelium discoideum UNSPECIFIED RACK1 UNSPECIFIED WD-repeat proteins UNSPECIFIED
Date of oral exam:	24 June 2014
Referee:	Name Academic Title Noegel, Angelika Prof. Dr. Hülskamp, Martin Prof. Dr. Arndt, Hartmut Prof. Dr.
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/5634