Many microtubule motors have been shown to couple to endosomal membranes. These motors include dynein as well as many different kinesin family members. Sorting nexins (SNXs) are central to the organization and function of endosomes. These proteins can actively shape endosomal membranes and couple directly or indirectly to the minus-end microtubule motor dynein. Motor proteins acting on endosomes drive their motility, dictate their morphology and impact on cargo segregation. We have used well-characterized members of the sorting nexin family to elucidate motor coupling using high resolution light microscopy coupled with depletion of specific microtubule motors. Endosomal domains labelled with sorting nexins 1, 4, and 8 (SNX1, SNX4, SNX8) couple to discrete combinations of dynein and kinesin motors. These specific combinations govern the structure and motility of each SNX-coated membrane as well as the segregation of distinct functional endosomal subdomains. Together our data show that these key features of endosome dynamics are governed by the same set of opposing microtubule motors. Thus, microtubule motors help to define the mosaic layout of endosomes that underpins cargo sorting.
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