dynactinin

Dynactinin is a term sometimes used in the literature to refer to the dynactin complex, a multi-subunit protein complex that regulates cytoplasmic dynein. The phrase dynactin (often the preferred term) denotes a large cofactor that enhances dynein’s movement along microtubules and helps recruit dynein to various cellular cargos. In some contexts dynactinin may be used to describe one or more subunits of the dynactin complex, but the standard nomenclature emphasizes the entire dynactin assembly.

The dynactin complex is a ≈1 MDa assembly composed of several subunits. A central component is the actin-related protein Arp1, which forms a small filament at the core. The p150Glued subunit (DCTN1) binds both dynein and microtubules and is important for activating dynein-driven transport. Other subunits—dynamitin/p50 (DCTN2), p24 (DCTN3), p62 (DCTN4), p27 (DCTN5), and p22 (DCTN6)—stabilize the complex and contribute to cargo binding and regulation.

Functionally, the dynactin complex links dynein to diverse intracellular cargos such as endosomes, lysosomes, mitochondria, and vesicles, enabling retrograde transport toward the microtubule minus ends. It also modulates dynein processivity and interacts with various cargo adaptors and regulatory proteins, thereby influencing cargo specificity and transport dynamics. Dynactin participates in other cellular processes that require dynein, including spindle positioning and chromosome movement during mitosis, as well as organelle positioning and trafficking in neurons.

Dysfunction or mutation of dynactin subunits, especially DCTN1, has been linked to neurodegenerative diseases and motor neuron pathologies in animal models and humans. Research on dynactin continues to elucidate its roles in intracellular transport, disease mechanisms, and potential therapeutic targets.