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Short answer: Kinesin is a motor protein. Conventional kinesin (kinesin-1) uses the energy of ATP hydrolysis to carry cargo along microtubules, taking alternating 8 nanometer steps toward the microtubule plus end. It is the founding member of a larger superfamily of molecular motors.
Definition and scope
According to the 2014 eLife structural study by Shang and colleagues, conventional kinesin is “the founding member of a superfamily of molecular motors that use the energy of ATP hydrolysis to transport cargo along microtubules,” with essential roles in a wide variety of cellular processes, most notably mitosis and neuronal transport. “Kinesin” therefore names a superfamily, and kinesin-1 is the conventional member that most structural work describes. This page covers kinesin-1 as it is described in those primary sources. It is background for researchers and lab staff and gives no clinical advice.
Kinesin work sits within cell biology, where motors are studied as part of how cells organise internal transport, and within biophysics, where single-molecule stepping and force generation are measured. Neuronal transport also connects it to neurobiology.
How kinesin-1 works
Kinesin-1 dimerizes through an extended stalk domain that forms a coiled coil. The two catalytic motor domains sit at one end of the coiled coil, and the cargo-binding domains sit at the opposite end (Shang et al., 2014). During active movement the dimerized motor domains take alternating, eight nanometer steps toward the microtubule plus end, tracking along single protofilaments.
Each motor domain cycles between conformations that are strongly attached to the microtubule and conformations that are weakly attached. The cycle is coordinated by the binding and breakdown of ATP. A short element called the neck linker docks along the motor domain when ATP binds, and this docking moves cargo toward the plus end. A flexible neck region lets each motor domain move past the other, and each step needs one domain to associate tightly with the microtubule and then release.
The crystal structure of the human kinesin-1 motor domain bound to tubulin (Gigant et al., 2013) adds two points: microtubule-stimulated ATP hydrolysis releases the motor domain from the microtubule, and ATP binding favours neck-linker docking, which biases the second head’s attachment toward the direction of movement.
Labelled parts and what each does
The table below maps the parts named by Shang et al. (2014) to their roles, so a reader can match terms in a paper or structure record to a function.
| Part | Where it sits | What the source says it does |
|---|---|---|
| Motor domain (two per dimer) | One end of the coiled-coil stalk | Catalytic domain that binds and breaks down ATP; cycles between strongly and weakly microtubule-attached states |
| Neck linker | Docks along the motor domain | Docks along the motor domain when ATP binds, moving cargo toward the microtubule plus end |
| Coiled-coil stalk | Extended domain that carries the motor domains at one end | Dimerizes kinesin-1 by forming a coiled coil |
| Cargo-binding domains | Opposite end of the coiled coil from the motors | Cargo end of the molecule |
One step, in order
- ATP binds a motor domain that is attached to the microtubule.
- The neck linker docks along that motor domain, which moves cargo toward the plus end and biases the other head’s attachment in the direction of travel.
- The dimer takes an eight nanometer step toward the plus end.
- Microtubule-stimulated ATP hydrolysis releases a motor domain from the microtubule, and the cycle repeats with the heads alternating.
Types and related concepts
Kinesin-1 is called conventional kinesin; it is one member of a superfamily, so “kinesin” on its own can mean the whole family or kinesin-1 specifically. Check which one a paper means before comparing results. This page describes kinesin-1 and does not list the other superfamily members.
Where it matters for labs and reagent decisions
A structure record states which species each chain came from. The RCSB Protein Data Bank entry 4HNA, “Kinesin motor domain in the ADP-MG-ALFX state in complex with tubulin and a DARPIN,” pairs human kinesin-1 heavy chain with sheep (Ovis aries) tubulin. It was solved by X-ray diffraction at 3.19 Å resolution and released on 2013-06-12.
When you read any motor-protein record, a short checklist from the fields on that page keeps the comparison honest:
- Which organism supplied each chain (here: human kinesin, sheep tubulin).
- Which nucleotide state the structure captures (here: ADP-MG-ALFX).
- The method and resolution (here: X-ray, 3.19 Å).
- The release date and the citation behind the record.
- Which other molecules are in the complex (here: a DARPin).
These details bear on whether results from one record can be compared with experiments run with a different species or nucleotide state. For methods that image single molecules or tracks, see super-resolution microscopy.
Common misunderstandings
- “Kinesin” is not one protein. It is a superfamily; kinesin-1 is the conventional member.
- The two heads do not move together. They take alternating steps, with each domain attaching tightly and then releasing.
- A structure is a snapshot. Entry 4HNA captures one nucleotide state, not the whole cycle.
- Structure records can mix species. 4HNA combines human kinesin with sheep tubulin.
FAQ
What does kinesin do?
Kinesin-1 uses ATP hydrolysis to transport cargo along microtubules, with essential roles in processes such as mitosis and neuronal transport.
Which way does kinesin-1 move?
Toward the microtubule plus end, in alternating eight nanometer steps.
What is the neck linker?
A structural element that docks along the motor domain when ATP binds, which moves cargo toward the plus end.
Is kinesin the same as kinesin-1?
No. Conventional kinesin (kinesin-1) is the founding member of the kinesin superfamily.
For related cell-level context, compare cell biology and molecular biology.
Sources
- Shang Z, et al. (2014). High-resolution structures of kinesin on microtubules provide a basis for nucleotide-gated force-generation. eLife. elifesciences.org/articles/04686 (checked 2026-10-29).
- RCSB Protein Data Bank, entry 4HNA. rcsb.org/structure/4hna (checked 2026-10-29).
- Gigant B, et al. (2013). Structure of a kinesin-tubulin complex and implications for kinesin motility. Nature Structural and Molecular Biology 20:1001-1007. doi.org/10.1038/nsmb.2624 (checked 2026-10-29).
