Myosin calmodulin binding domain

Fig. 9. Helical net diagram (Crick, 1953) of a model calmodulin-binding peptide and the putative calmodulin-binding domains of two forms of myosin light-chain kinase (MLCK). The sequences are drawn together on a single helical net and are taken from (clockwise from left) the model peptide described by DeGrado et al. (1985), skeletal muscle MLCK peptide 342-359 (Edelman et al., 1985), and the N-terminal 18 residues of a peptide derived from smooth muscle MLCK (Lucas et al., 1986). The amino acids in the sequences are given in single letter codes. Positions that are hydrophobic in all three sequences are indicated by shading.

Kemp BE, Pearson RB, Guerriero V Jr, Bagchi 1C, Means AR (1987) The calmodulin binding domain of chicken smooth muscle myosin light chain kinase contains a pseudosubstrate sequence. J Biol Chem 262 2542-2548 Kenney RE, Hoar PE, Kerrick WG (1990) The relationship between ATPase activity, isometric force, and myosin l ht-chain phosphorylation and thiophosphorylation in skinned smooth muscle fiber bundles from chicken gizzard. J Biol Chem 265 8642-8649... 

Fig. 6.10. Structure of Ca -cal-modulin. a) Structure of free Ca -calmodulin. Calmodulin is composed of two domains that can each bind two Ca ions. Both domains are linked via a flexible structural element. The Ca ions are represented as spheres. MOLSKRIPT representation according to Krauhs, (1991). b) Ca -calmodulin in complex with a peptide that is derived from the Ca -binding domain of the myosin light chain kinase. Ca -calmodulin is represented as a band, and the peptide substrate is a ball and stick" model. The perspective is along the longitudinal axis of the hnear peptide substrate.

The 20-amino acid residue peptide RS-20, whose sequence derives from smooth muscle myosin light chain kinase (MLCK), is a well-known calmodulin binding peptide [144], Both, RS-20 and LMS-1, a 13-residue peptide derived from the autoinhibitory domain of MLCK, have the capability of inhibiting MLCK phosphorylation activity, normally directed toward the molecular motor, actin binding protein myosin II, which is involved in physiological phenomena like cell polarization and locomotion [145, 146]. 

Lukas TJ, Burgess WH, Prendergast FG, Lau W, Watterson DM (1986) Calmoduhn binding domains characterization of a phosphorylation and calmodulin binding site from myosin light chain kinase. Biochemistry 25 1458-1464... 

Figure 11.9 (Left) The EF hand helix-loop-helix motif (centre) rat testes calmodulin. The globular domains each have two Ca2+-binding sites, indicated by white spheres, connected by a seven-turn a-helix (right) two views of the (Ca2+)4 fruit fly calmodulin in complex with its 26-residue target peptide from rabbit skeletal muscle myosin light chain kinase, ((left, centre) From Voet and Voet, 2004. Reproduced with permission from John Wiley Sons., Inc. and (right) Carafoli, 2002. Copyright (2002) National Academy of Sciences, USA.)...

There is an additional controlling pathway which is thin filament regulated this is dependent upon another protein, caldesmon, which is closely associated with the actin/tropomyosin-myosin domain. Caldesmon derives its name fi-om its intrinsic ability to bind to calmodulin with a much greater affinity than to the thin... 

Figure 2. Improvement of yellow cameleon by using a circularly permuted YFP variant. (A) The three-dimensional structure of GFP with the positions of the original (Metl) and new N-termini (Aspl73). (B) Domain structures of YCS.12 and YC3.60. CaM, Xenopus calmodulin Ml3, a CaM binding peptide derived from myosin light chain kinase (C, D) Emission spectra of YCS. 12 (C) and YC3.60 (D) (excitation at 435 nm) at zero (doted line) and saturated Ca (solid line). (E) A series of confocal pseudo-B/W images showing propagation of [Ca c- These images were taken at...

In the iwesence of calcium, calmodulm is known to intoract with a number of proteins and peptides. One example is binding of a peptide from myosin light-chain kinase (MLCK) to calmodulin. Such peptides are known to bind in thecleft between the two domains of calmodulin (Figure 13.12). When bound to calmodulin, the MLCK peptide... 

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