Myosin peptide chains

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.)...

In the keratins, large parts of the peptide chain show right-handed a-helical coiling. Two chains each form a left-handed superhelix, as is also seen in myosin (see p. 65). The superhelical keratin dimers join to form tetramers, and these aggregate further to form protofilaments, with a diameter of 3 nm. Finally, eight protofilaments then form an intermediate filament, with a diameter of 10 nm (see p.204). 

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.

AKKLSKDRMAAYMARRK <3> (<3> synthetic peptide, analog of inhibitory region of myosin light chain kinase [26]) [26]... 

Toeroek, K. Cowley, D.J. Brandmeier, B.D. Howell, S. Aitken, A. Tren-tham, D.R. Inhibition of calmodulin-activated smooth-muscle myosin light-chain kinase by calmodulin-binding peptides and fluorescent (phosphodiesterase-activating) calmodulin derivatives. Biochemistry, 37, 6188-6198 (1998)... 

Myosin Light Chain Kinase Autoinhibitory Peptide (LSM-1) 2 M ... 

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.

Twelve ACE-inhibitory peptides have been identified from sardine muscle hydrolysate, revealing that a dipeptide, Val-Tyr, acts as a key inhibitor (Matsufuji et al., 1994). Of the identified ACE-inhibitory peptides, the tripeptides (Leu-Arg-Pro, lie-Val-Tyr) and the dipeptide (Val-Tyr) show strong inhibitory activity. Moreover, two inhibitory peptides (myopentapep-tides A and B) have been purified from a thermolysin digest of porcine skeletal muscle proteins. The sequences were found in the primary structure of the myosin heavy chain (Arihara et al., 2001). 

The peptide substrate was phosphorylated in a reaction mixture (0.25 mL) containing 25 mA/ Tris-HCl (pH 7.5), 0.5 mg/mL bovine serum albumin, 4.0 mA/ MgCl2, 0.2 mA/ CaCl2, 2.6 nM calmodulin, 24 fiM peptide, 1.5 nA/ myosin light chain kinase, and 400 fiM ATP. The reaction was started by adding ATP. After 30 minutes at 28°C, the reaction was terminated by adding 0.1 mL of 10% acetic acid. Aliquots were directly applied to the HPLC column. The reaction was linear for up to 60 minutes. 

Figure 7 Structures of calmodulin (blue) complexed to a peptide (yellow) from (a) CaMKK (1IQ5), (b) CaMKII (1CM1), (c) rabbit skeletal myosin light chain kinase (SLMK) (2BBM), and (d) glutamate decarboxylase (INWD) ...

Fig. 6 Localization of key cardiac myocyte phenotypic markers of day 21 ECMs and BMSCs tube co-cultured in basal medium. Images demonstrate the expression of (a) sarcomeric myosin heavy chain (MF20), (b) cardiac troponin I, (c) a-actinin, (d) N-cadherin, (e) Gata4, (f) atrial natriuretic peptide (ANP), (g) desmin, and (h) connexin 43. Reproduced with permission from Valarmathi et al. [147]...

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