BIG1 is a binding partner of myosin IXb and regulates its Rho-GTPase activating protein activity
UMass Chan Affiliations
Department of PhysiologyDocument Type
Journal ArticlePublication Date
2005-01-13Keywords
ADP-Ribosylation Factor 1Animals
Cloning, Molecular
DNA, Complementary
Dose-Response Relationship, Drug
Electrophoresis, Polyacrylamide Gel
GTP-Binding Proteins
Guanine Nucleotide Exchange Factors
Humans
Immunoprecipitation
Inhibitory Concentration 50
Kidney
Mutation
Myosins
Plasmids
Protein Binding
Protein Structure, Tertiary
Rats
Recombinant Proteins
Signal Transduction
Time Factors
Two-Hybrid System Techniques
Zinc Fingers
rho GTP-Binding Proteins
rhoA GTP-Binding Protein
Life Sciences
Medicine and Health Sciences
Metadata
Show full item recordAbstract
Myosin IXb, a member of the myosin superfamily, is a molecular motor that possesses a GTPase activating protein (GAP) for Rho. Through the yeast two-hybrid screening using the tail domain of myosin IXb as bait we found BIG1, a guanine nucleotide exchange factor for ADP-ribosylation factor (Arf1), as a potential binding partner for myosin IXb. The interaction between myosin IXb and BIG1 was demonstrated by co-immunoprecipitation of endogenous myosin IXb and BIG1 with anti-BIG1 antibodies in normal rat kidney cells. Using the isolated proteins, it was demonstrated that myosin IXb and BIG1 directly bind to each other. Various truncation mutants of the myosin IXb tail domain were produced, and it was revealed that the binding region of myosin IXb to BIG1 is the zinc finger/GAP domain. Interestingly, the GAP activity of myosin IXb was significantly inhibited by the addition of BIG1 with IC(50) of 0.06 microm. The RhoA binding to myosin IXb was inhibited by the addition of BIG1 with the concentration similar to the inhibition of the GAP activity. Likewise, RhoA inhibited the BIG1 binding of myosin IXb. These results suggest that BIG1 and RhoA compete with each other for the binding to myosin IXb, thus resulting in the inhibition of the GAP activity by BIG1. The present study identified BIG1, the Arf guanine nucleotide exchange factor, as a new binding partner for myosin IXb, which inhibited the GAP activity of myosin IXb. The findings raise a concept that the myosin transports the signaling molecule as a cargo that functions as a regulator for the myosin molecule.Source
J Biol Chem. 2005 Mar 18;280(11):10128-34. Epub 2005 Jan 11. Link to article on publisher's siteDOI
10.1074/jbc.M413415200Permanent Link to this Item
http://hdl.handle.net/20.500.14038/42339PubMed ID
15644318Related Resources
Link to Article in PubMedae974a485f413a2113503eed53cd6c53
10.1074/jbc.M413415200
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