RGD Reference Report - Localization of myosin 1b to actin protrusions requires phosphoinositide binding.

General

Localization of myosin 1b to actin protrusions requires phosphoinositide binding.
Authors:	Komaba, S Coluccio, LM
Citation:	Komaba S and Coluccio LM, J Biol Chem. 2010 Sep 3;285(36):27686-93. doi: 10.1074/jbc.M109.087270. Epub 2010 Jul 7.
RGD ID:	8554686
Pubmed:	PMID:20610386 (View Abstract at PubMed)
PMCID:	PMC2934636 (View Article at PubMed Central)
DOI:	DOI:10.1074/jbc.M109.087270 (Journal Full-text)
Myosin 1b (Myo1b), a class I myosin, is a widely expressed, single-headed, actin-associated molecular motor. Transient kinetic and single-molecule studies indicate that it is kinetically slow and responds to tension. Localization and subcellular fractionation studies indicate that Myo1b associates with the plasma membrane and certain subcellular organelles such as endosomes and lysosomes. Whether Myo1b directly associates with membranes is unknown. We demonstrate here that full-length rat Myo1b binds specifically and with high affinity to phosphatidylinositol 4,5-bisphosphate (PIP(2)) and phosphatidylinositol 3,4,5-triphosphate (PIP(3)), two phosphoinositides that play important roles in cell signaling. Binding is not Ca(2+)-dependent and does not involve the calmodulin-binding IQ region in the neck domain of Myo1b. Furthermore, the binding site is contained entirely within the C-terminal tail region, which contains a putative pleckstrin homology domain. Single mutations in the putative pleckstrin homology domain abolish binding of the tail domain of Myo1b to PIP(2) and PIP(3) in vitro. These same mutations alter the distribution of Myc-tagged Myo1b at membrane protrusions in HeLa cells where PIP(2) localizes. In addition, we found that motor activity is required for Myo1b localization in filopodia. These results suggest that binding of Myo1b to phosphoinositides plays an important role in vivo by regulating localization to actin-enriched membrane projections.

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Cellular Component

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Term	Qualifier	Evidence	With	Reference	Notes	Source	Original Reference(s)
cell periphery	located_in	IDA		8554686	PMID:20610386	UniProt
filopodium	located_in	IDA		8554686	PMID:20610386	UniProt

Molecular Function

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Term	Qualifier	Evidence	With	Reference	Notes	Source	Original Reference(s)
phosphatidylinositol-3,4,5-trisphosphate binding	enables	IDA		8554686	PMID:20610386	UniProt
phosphatidylinositol-4,5-bisphosphate binding	enables	IDA		8554686	PMID:20610386	UniProt

Objects Annotated

Genes (Rattus norvegicus)

Myo1b (myosin Ib)

Additional Information

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Localization of myosin 1b to actin protrusions requires phosphoinositide binding.