Key result
Myosin VI heavy chains associated with clathrin-mediated endocytic vesicles undergo homoFRET, indicating they are precisely positioned to bring their tail domains into close proximity and function as a processive dimer.
Myosin VI heavy chains are precisely positioned on endocytic vesicles to allow dimerization, supporting its function as a processive dimer in intracellular trafficking.
Does not inform clinical practice; extends models of myosin VI as a processive dimer in endocytosis.
Myosin VI has been studied in both a monomeric and a dimeric form in vitro. Because the functional characteristics of the motor are dramatically different for these two forms, it is important to understand whether myosin VI heavy chains are brought together on endocytic vesicles. We have used fluorescence anisotropy measurements to detect fluorescence resonance energy transfer between identical fluorophores (homoFRET) resulting from myosin VI heavy chains being brought into close proximity. We observed that, when associated with clathrin-mediated endocytic vesicles, myosin VI heavy chains are precisely positioned to bring their tail domains in close proximity. Our data show that on endocytic vesicles, myosin VI heavy chains are brought together in an orientation that previous in vitro studies have shown causes dimerization of the motor. Our results are therefore consistent with vesicle-associated myosin VI existing as a processive dimer, capable of its known trafficking function.
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Altman et al. (2007) studied this question. GFP-tagged Myosin VI constructs was evaluated on Fluorescence anisotropy (homoFRET). Myosin VI heavy chains associated with clathrin-mediated endocytic vesicles undergo homoFRET, indicating they are precisely positioned to bring their tail domains into close proximity and function as a processive dimer.
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