The actin-based molecular motor myosin VI functions in the endocytic uptake pathway, both during the early stages of clathrin-mediated uptake and in later transport to/from early endosomes. This study uses fluorescence recovery after photobleaching (FRAP) to examine the turnover rate of myosin VI during endocytosis. The results demonstrate that myosin VI turns over dynamically on endocytic structures with a characteristic half life common to both the large insert isoform of myosin VI on clathrin-coated structures and the no insert isoform on early endosomes. This half life is shared by the myosin VI binding partner Dab2 and is identical for fulllength myosin VI and the cargo-binding tail region. The four fold slower half life of an artificially dimerized construct of myosin VI on clathrin-coated structures suggests that wildtype myosin VI does not function as a stable dimer, but either as a monomer or in a monomer/dimer equilibrium. Taken together, these FRAP results offer insight into both the basic turnover dynamics and the monomer/dimer nature of myosin VI.
|Heissler, Sarah M; Selvadurai, Jayashankar; Bond, Lisa M et al. (2012) Kinetic properties and small-molecule inhibition of human myosin-6. FEBS Lett 586:3208-14|
|Bond, Lisa M; Brandstaetter, Hemma; Sellers, James R et al. (2011) Myosin motor proteins are involved in the final stages of the secretory pathways. Biochem Soc Trans 39:1115-9|
|Bond, Lisa M; Peden, Andrew A; Kendrick-Jones, John et al. (2011) Myosin VI and its binding partner optineurin are involved in secretory vesicle fusion at the plasma membrane. Mol Biol Cell 22:54-65|