Myosin II
(Actin Binding Protein)
Cat. #: 8326-01
Applications
Myosin II is a filament-forming, actin-activated mechanochemical ATPase that converts the free energy of ATP hydrolysis into force and relative sliding between actin and myosin. In reconstituted systems, it is broadly used to generate active stresses in actin networks and bundles, enabling quantitative studies of contractility, tension build-up, and force transmission under precisely defined buffer and crowding conditions.
Typical applications include actin gliding and in vitro motility formats (surface-immobilized myosin), reconstitution of minimal contractile assemblies (e.g., rings, cortices, and active gels), and biophysical assays that read out actomyosin kinetics and mechanics (e.g., ATPase coupling, load-dependent interactions, and network-scale contraction). The nucleotide state governs actin affinity (strong-binding states in rigor/ADP; weak-binding states upon ATP binding), which can be exploited to control attachment, sliding, and contraction in assay workflows.
Description
| Protein | Myosin II |
| Origin | Skeletal muscle, rabbit (m. psoas) |
| Molecular mass | ~480 kDa |
| Protein description |
Fast skeletal muscle myosin II from rabbit psoas muscle is a hexameric motor complex composed of two heavy chains and four light chains (two essential and two regulatory light chains). Each heavy chain contributes an N-terminal motor domain (actin- and nucleotide-binding site) and a lever arm that is stabilized by the bound light chains, supporting chemomechanical coupling during the ATPase cycle. The C-terminal tail forms a long α-helical coiled-coil that mediates dimerization and enables self-assembly into bipolar thick filaments under low-ionic-strength conditions. This intrinsic filament-forming property makes full-length myosin II particularly suitable for minimal actomyosin systems where collective motor activity (multiple heads working in parallel) drives macroscopic force generation and contraction. |
| Actin interaction | Binds to F-actin in a nucleotide-state dependent manner (strong binding in rigor/ADP states; reduced affinity upon ATP binding). |
Properties
| Form | Lyophilized, ready-to-use. |
| Quantity per unit | 2 × 100 µg |
| Buffer | 500 mM KCl, 50 mM HEPES pH 7.0, 1 mM TCEP, 0.5 mM EDTA, 10% sucrose (upon reconstitution with 0.1 ml ultrapure water to obtain 1 mg/ml) |
| Purity | >98% by scanning densitometry from Coomassie G-250 stained SDS gels. |
| Purification notes | Purified from rabbit skeletal muscle (m. psoas). |
| Protein concentration | Determined by Biuret method with actin (rabbit skeletal muscle) as reference. |
| Storage instructions | Upon reconstitution store on ice during use. For longer-term storage, the product can also be stored as a glycerol stock at -20°C. Avoid repeated freeze/thaw cycles. Reconstitute gently (avoid foaming/vortexing); if necessary, clarify briefly to remove aggregates before sensitive biophysical measurements. |
| Shipping conditions | At ambient temperature. Upon delivery store at -70°C. |
| Remarks | For coated or filamentous myosin II, MotorMix I (Cat. #: 5502-01) or PolyMix (Cat. #: 5000-0*) can be used. For soluble myosin II, MotorMix II (Cat. #: 5503-01) is required. Assay note: Myosin II can self-assemble into bipolar filaments when ionic strength is lowered; maintain sufficiently high ionic strength during handling when a predominantly soluble state is desired, and adjust ionic conditions deliberately when filament formation is intended. |
| CAS no. |
Proteins and buffers from Hypermol® are made of the ultrapure reagents in Milli-Q™ water, as described in our publications.
Further Information
Material and Safety Data Sheet
References
Reconstitution of contractile actomyosin rings in vesicles.
Litschel T, Kelley CF, Holz D, Adeli Koudehi M, Vogel SK, Burbaum L, Mizuno N, Vavylonis D, Schwille P. Nat Commun. 2021 Apr 15;12(1):2254. doi: 10.1038/s41467-021-22422-7.
Synthetic thick filaments: A new avenue for better understanding the myosin super-relaxed state.
J. Biol. Chem. (2020). doi: 10.1074/jbc.RA120.016506.
Product DataSheetMaterial and Safety Data Sheet
Reconstitution of contractile actomyosin rings in vesicles.
Litschel T, Kelley CF, Holz D, Adeli Koudehi M, Vogel SK, Burbaum L, Mizuno N, Vavylonis D, Schwille P.Nat Commun. 2021 Apr 15;12(1):2254. doi: 10.1038/s41467-021-22422-7.
