Inhibitor SourceBook™ Second Edition

Myosin Light Chain Kinase (MLCK) Inhibitors
Myosin light chain kinase (MLCK), a Ca 2+ -calmodulin
dependent multi-functional enzyme, plays a critical
role in the regulation of smooth muscle contraction and
cellular migration. It regulates the contractile interaction
between actin microfilaments and conventional smooth
muscle and non-muscle myosin II. MLCK is composed of
an N-terminal actin-binding domain, a central kinase
domain, and a C-terminal myosin-binding domain. The
kinase domain activates the interaction of smooth-muscle
myosin with actin by phosphorylating the myosin light
chain. MLCK phosphorylates a specific site on the Nterminus
of the regulatory light chain of myosin II. This
phosphorylation is responsible for coupling increased Ca 2+
concentration with smooth muscle contraction.
In the presence of Ca 2+ , the C-terminal domain of
calmodulin binds to the N-terminus of the calmodulinbinding
sequence of MLCK followed by the binding
Myosin Light Chain Kinase (MLCK) Inhibitors
Calbiochem • Inhibitor SourceBook
Phosphorylation/Dephosphorylation
of the N-terminal domain to the C-terminus of the
calmodulin-binding sequence. MLCK is reported to
bind the actin filament in a manner that also allows the
simultaneous binding of the other major thin filament
components; calponin, tropomyosin, etc. The binding site
is suggested to be on the outside of sub-domain 1. There
is approximately one MLCK molecule for every 100 actin
molecules in smooth muscle and each MLCK contains at
least three of the DFRXXL motifs allowing each molecule
to bind three actins (K d = 4 mM).
References:
Kamm, K.E., and Stull, J.T. 200 . J. Biol. Chem. 276, 4527.
Hatch, V., et al. 200 . J. Cell Biol. 154, 6 .
Smith, L., and Stull, J.T. 2000. FEBS let. 480, 298.
Le, L-H., et al. 999. Proc. Natl. Acad. Sci. USA 96, 6666.
Sellers, J.R., and Pato, M.D. 984. J.Biol.Chem. 259, 7740.
Product Cat. No. Comments Size Price
A3, Hydrochloride 100122 [N-(2-Aminoethyl)-5-chloronaphthalene-1-sulfonamide, HCl]
A shorter alkyl chain derivative of W-7 (Cat. No. 68 629) that inhibits MLCK
(K i = 7.4 mM), CK I (K i = 80 mM), CK II (K i = 5. mM), PKA (K i = 4.3 mM), PKC (K i = 47 mM),
and PKG (K i = 3.8 mM).
Gö 7874, Hydrochloride 365252 A potent and selective inhibitor of protein kinase C (IC 50 = 4 nM for rat brain PKC).
Inhibits protein kinase A (IC 50 = 5 0 nM), protein kinase G (IC 50 = 4.8 mM), and myosin
light chain kinase (IC 50 = 20 nM) at much higher concentrations.
K-252a, Nocardiopsis
sp.
InSolution K-252a,
Nocardiopsis sp.
K-252b, Nocardiopsis
sp.
420298 A cell-permeable inhibitor of MLCK (K i = 7 nM), CaM kinase II (K i = .8 nM), PKC
(K i = 25 nM), and PKG (K i = 20 nM). Also acts as a potent inhibitor (IC 50 = 3 nM) of the
protein tyrosine kinase activity of the NGF receptor gp 40 trk .
0 mg $90
500 mg $ 00
00 mg $ 33
420297 A mM ( 00 mg/2 4 ml) solution of K-252a (Cat. No. 420298) in anhydrous DMSO. 00 mg $ 28
420319 A non-selective inhibitor of MLCK (K i = 47 nM), PKA (K i = 90 nM), PKC (K i = 20 nM),
and PKG (K i = 00 nM).
ML-7, Hydrochloride 475880 [1-(5-Iodonaphthalene-1-sulfonyl)homopiperazine, HCl]
A cell-permeable, potent and selective inhibitor of MLCK (K i = 300 nM).
Inhibits PKA (K i = 2 mM) and PKC (K i = 42 mM) at much higher concentrations.
ML-9, Hydrochloride 475882 [1-(5-Chloronaphthalene-1-sulfonyl)homopiperazine, HCl]
A cell-permeable inhibitor of MLCK (K i = 3.8 mM), PKA (K i = 32 mM), and
PKC (K i = 54 mM).
Myosin Light Chain
Kinase Inhibitor Peptide
8
475981 (H-RKKYKYRRK-NH 2 ; MLCK Inhibitor Peptide 18)
A highly basic nonapeptide that acts as a selective inhibitor of MLCK (IC 50 = 50 nM).
Does not block calmodulin (CaM) or inhibit the activities of CaM Kinase II or PKA.
Piceatannol 527948 (trans-3,3´,4,5´-Tetrahydroxystilbene)
A plant metabolite that preferentially inhibits the activity of p72 Syk (IC 50 ~ 0 mM).
Also acts as an inhibitor of rat liver PKA catalytic subunit (IC 50 = 3 mM), PKC
(IC 50 = 8 mM), and MLCK (IC 50 = 2 mM).
Staurosporine,
Streptomyces sp.
More online... www.calbiochem.com/inhibitors/MLCK
569397 A potent, cell-permeable broad-spectrum inhibitor of protein kinases. Inhibits MLCK
(IC 50 = .3 nM), CaM kinase (IC 50 = 20 nM), PKA (IC 50 = 7 nM), PKC (IC 50 = 700 pM),
and PKG (IC 50 = 8.5 nM).
50 mg
00 mg
$76
$ 33
mg $99
mg $99
5 mg $ 6
00 mg
250 mg
mg $4
$ 43
$302
Technical Support
Phone 800 628 8470
E-mail calbiochem@emdbiosciences.com
29