Asymmetries in kinesin-2 and cytoplasmic dynein contributions to melanosome transport

•We studied the collective action of kinesin-2 and dynein during melanosome transport.•The stiffness of the motor complex linking organelles to microtubules was determined.•The stiffness was obtained from fluctuations perpendicular to the transport direction.•The stiffness and organelle speed depended on the organelle size and cargo direction.•Melanosome transport is driven by asymmetric teams of dynein and kinesin-2 motors. The mechanisms involved in bidirectional transport along microtubules remain largely unknown. We explored the collective action of kinesin-2 and dynein motors during transport of melanosomes in Xenopus laevis melanophores. These motors are attached to organelles through accessory proteins establishing a complex molecular linker. We determined both the stiffness of this linker and the organelles speed and observed that these parameters depended on the organelle size and cargo direction. Our results suggest that melanosome transport is driven by two dissimilar teams: whereas dynein motors compete with kinesin-2 affecting the properties of plus-end directed organelles, kinesin-2 does not seem to play a similar role during minus-end transport.