Essential light chain

FIGURE 8 Coomassie blue-stained 2D electrophoretogram of porcine carotid arterial proteins. LC17, LC17a, and LClTb isoforms LC20, multiple forms of LC20 TM, tropomyosin. 

Based on the amino acid sequence, the slower LC17a was named LClTnm (nonmuscle type) and the faster LClTb as LClTgi (gizzard type) (Hasegawa etal., 

In this nomenclature, the nonmuscle LC17a is the more basic and the gizzard type smooth muscle LClTb is the more acidic isoform (Kelley et al., 1993), and therefore the LClTb of urea-PAGE corresponds to the LClTa of the 2D gel and the LClTa of the former corresponds to the LClTb of the latter. In this review, we shall refer to LClTa as the more acidic and LClTb as the more basic isoform, and will make the appropriate corrections in the data presentation of the reverse designations. 

The distribution of the LClTa and LClTb in different types of smooth muscles is shown in Table I. In many cases, LClTa is the major isoform and it is the only isoform in most mammalian gastrointestinal muscles and chicken gizzard. In uterus, LClTa gradually increases during pregnancy, whereas in the nonpregnant state LClTb is the predominant isoform. There is some variation in the isoform distribution when the same tissue is analyzed by different laboratories or even by the same laboratory. 

Two isoforms of LC17 have been separated by 2D gel electrophoresis in human uterus (Cavaille et al., 

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Dominguez, R., Freyzon, Y., Trybus, K. M., and Cohen, C. (1998). Crystal structure of a vertebrate smooth muscle myosin motor domain and its complex with the essential light chain Visualization of the pre-power stroke state. Cell 94, 559-571. 

Timson, D.J., Trayer, H. R., and Trayer, I. P. (1998). The N-terminus of Al-type myosin essential light chains binds actin and modulates myosin motor function. Eur. 

Ethylene glycol bis((3-aminoethyl ether) N,N -tetraacetic acid Essential light chain Endoplasmic reticulum... 

Trybus KM (1994) Regulation of expressed truncated smooth muscle myosins. Role of the essential light chain and tail length. J Biol Chem 269 20819-20822... 

The structures used here contain that part of the amino terminus of myosin (residues 1 to 835) just sufficient to include the essential and regulatory light chains. Thus, the cross-bridge is composed of three chains—approximately 800 residues from the amino terminus of the myosin chain, the essential light chain, and the regula-... 

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