Kif13Edit
KIF13, short for kinesin family member 13, refers to a pair of motor proteins in humans that belong to the kinesin-3 family. The two paralogs, KIF13A and KIF13B, act as plus-end–directed microtubule motors that convert chemical energy from ATP hydrolysis into mechanical work to move cargo-bearing vesicles and organelles within the cell. These motors are especially important for trafficking in polarized cell types and for delivering signaling receptors and membrane components to specific plasma membrane domains. In the cell biology literature, KIF13A and KIF13B are frequently described as key players in recycling endosome transport, epithelial polarity, and neuronal development. Kinesin-3 KIF13A KIF13B endosome microtubule
Structure and function
Molecular architecture
KIF13A and KIF13B share a canonical kinesin-3 design: an N-terminal motor domain responsible for ATP hydrolysis and microtubule binding, followed by a long coiled-coil stalk and a C-terminal tail that engages cargo or cargo-adaptor proteins. This modular arrangement allows the motors to recognize diverse vesicular cargos and coordinate their movement along the microtubule network. The motor domain confers processive movement toward the plus ends of microtubules, enabling rapid and targeted delivery of vesicles within cells. motor protein microtubule
Paralogs and isoforms
KIF13A and KIF13B are the two primary paralogs in humans. They are expressed in a variety of tissues, with notable enrichment in brain tissue and in polarized epithelia, where directional trafficking is essential for proper cell function. Although highly similar in structure, the two proteins can differ in cargo preferences and regulatory interactions, contributing to their distinct physiological roles. KIF13A KIF13B brain epithelial cell
Cellular roles
Endocytic recycling and trafficking
A major theme for KIF13A and KIF13B is the transport of cargo from recycling and endocytic compartments to the plasma membrane. In many cell types, these motors associate with Rab11-positive recycling endosomes and help deliver receptors and membrane components to the cell surface, thereby influencing receptor availability and signaling. The involvement of KIF13 motors in recycling pathways is linked to the broader machinery of endocytosis and membrane trafficking, including interactions with Rab11 and related adaptors. Rab11 endosome Transferrin receptor
Apical transport in polarized epithelia
In polarized epithelial cells, KIF13A and KIF13B contribute to the polarized delivery of apical cargos, supporting the maintenance of distinct apical and basolateral membrane domains. This role is central to tissue organization and barrier function, and it exemplifies how motor proteins integrate trafficking with cell polarity. cell polarity epithelial cell
Neuronal transport and development
In the nervous system, KIF13 family members participate in intracellular transport that supports neuronal development and synaptic function. Their activity can influence axonal and dendritic trafficking, growth cone dynamics, and receptor distribution, underscoring a role for these motors in neural connectivity and plasticity. neuron axon dendrite
Regulation and expression
Expression of KIF13A and KIF13B is developmentally regulated and subject to tissue-specific control. The motors are part of a broader network of intracellular transport that integrates signaling, membrane trafficking, and cytoskeletal dynamics. In model systems, reducing or altering KIF13 function can disrupt recycling traffic and polarity, highlighting their importance for cellular homeostasis. While the details of cargo specificity and regulation continue to be refined, the general picture places KIF13A and KIF13B as essential contributors to directional vesicle movement in multiple cell types. KIF13A KIF13B Rab11 cell polarity
Evolution and phylogeny
KIF13A and KIF13B are conserved components of the kinesin-3 clade across vertebrates and are studied in the context of the broader evolution of intracellular transport. The kinesin-3 family is characterized by rapid, high-processivity movement suited for fast vesicle trafficking, and KIF13 paralogs illustrate how gene duplication can diversify cargo recognition and tissue-specific roles within this motor class. Kinesin evolution