Biology Reference
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that they 'mark a spot' at the plasma membrane and dock the myosin I via
its SH3 domain.
The evidence that class I myosins and actin dynamics play a crucial role in
endocytosis in yeasts and other lower eukaryotes is overwhelming, however,
their involvement in the endocytic machinery of mammalian cells is still
acutely lagging. In this context, recent findings are extremely exciting and
highlight the likely conservation of these mechanisms. For example, Myo1B is
associated with endosomes and lysosomes (Raposo et al., 1999) and
cooperates with microtubules for the movement of lysosomes (Cordonnier
et al., 2001). Both calmodulin and Myo1C regulate membrane tracking
along the recycling pathway of MDCK cells (Huber et al., 2000). The
recycling of the glucose transporter in response to insulin is facilitated by
Myo1c (Bose et al., 2002). The major challenges for the future will be to
determine the roles played by actin filaments at different steps in the
internalization of proteins and fluid, and to determine how the interface of the
endocytic machinery and the actin cytoskeleton is structured and regulated.
Acknowledgements
I thank all the laboratory members who along the years have contributed to a
better understanding of myosin function, and especially to Eva Schwarz and
Claudia Kistler, who have generated all the data on D. discoideum MyoK,
including many exciting and still to be published results mentioned here. The
work has been supported by the Max-Planck Society,
the Deutsche
Forschungsgemeinschaft and the BBSRC.
References
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