CIB1 and CaBP1 bind to the myo1c regulatory domain

Myo1c is a member of the myosin-I family that binds phosphoinositides and links the actin cytoskeleton to cellular membranes. Recent investigations suggest that targeting of myo1c to some subcellular regions requires the binding of an unknown protein to the IQ motifs in the myo1c regulatory domain....

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Bibliographic Details
Published in:Journal of muscle research and cell motility 2007-08, Vol.28 (6), p.285-291
Main Authors: Tang, Nanyun, Lin, Tianming, Yang, Jun, Foskett, J Kevin, Ostap, E Michael
Format: Article
Language:English
Subjects:
Amino Acid Motifs
Animals
Calcium-Binding Proteins - metabolism
Calmodulin - metabolism
Cells
Chlorocebus aethiops
Competition
COS Cells
Mice
Myosin Type I - chemistry
Myosin Type I - metabolism
PC12 Cells
Protein Structure, Tertiary
Proteins
ras GTPase-Activating Proteins - metabolism
Rats
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Summary:Myo1c is a member of the myosin-I family that binds phosphoinositides and links the actin cytoskeleton to cellular membranes. Recent investigations suggest that targeting of myo1c to some subcellular regions requires the binding of an unknown protein to the IQ motifs in the myo1c regulatory domain. We identify two myristoylated proteins that bind the myo1c regulatory domain: calcium-binding protein 1 (CaBP1) and calcium- and integrin-binding-protein-1 (CIB1). CIB1 and CaBP1 interact with myo1c in vivo as determined by pull-down experiments and fluorescence microscopy where the endogenously expressed proteins show extensive cellular colocalization with myo1c. CIB1 and CaBP1 bind to the myo1c IQ motifs in the regulatory domain where they compete with calmodulin for binding. CaBP1 has a higher apparent affinity for myo1c than CIB1, and both proteins better compete with calmodulin in the presence of calcium. We propose that these proteins may play a role in specifying subcellular localization of myo1c.
ISSN:0142-4319
1573-2657
DOI:10.1007/s10974-007-9124-7