Kinesin-1 captures RNA cargo in its adaptable coils

The prototypic and ubiquitous microtubule motor, kinesin-1, uses a variety of adaptor proteins to facilitate the selective transport of diverse cargo within the cell. These cargo adaptors bind to the motor complex through interactions with the kinesin light or heavy chains (KLCs or KHCs). In this issue of Genes & Development, Dimitrova-Paternoga et al. (pp. 976–991) present the first structural characterization of a KHC–cargo adaptor interface. They describe an antiparallel heterotrimeric coiled-coil complex between the carboxy tail of KHC and Tm1-I/C (aTm1), the atypical tropomyosin that is important for oskar mRNA transport in Drosophila oocytes. This interaction enhances direct binding between KHC and RNA. Their findings demonstrate the structural plasticity of the KHC tail as a platform for protein–protein interactions and reveal how a cargo adaptor protein can modify a motor–RNA interface to promote transport.