Amino Acid Sequence and Coiled-Coil Structure

AMINO ACID SEQUENCE AND COILED-COIL STRUCTURE 

FIGURE 3 Amino add sequences of a- and p-TMs of chicken smooth muscle, products of two separate genes. The smooth muscle a-TM (SMa) sequence is as detailed by Lau et al., (1985) for the chicken gizzard protein with corrections at positions 172,199, 203, and 204 based on the cDNA sequence for chicken skeletal muscle a-TM reported by Gooding et al. (1987). The p-TM sequence is as reported by Sanders and Smillie (1985) for the gizzard protein and corroborated by cDNA (Helfman etal., 1984) and genomic DNA sequencing (Libri et al, 1989). Exon boundaries are indicated by the vertical lines. 

FIGURE 4 Comparison of skeletal and smooth muscle TM primary structures. Shaded areas represent alternatively spliced exons, which are different in the smooth muscle a- and p-TM chains when compared with those in skeletal muscle. Nonshaded areas are identical in smooth muscle and skeletal fast-twitch muscle a-TM chains. This is true also of the smooth and skeletal muscle p-TM chains. Exon boundaries for the a gene are for the highly homologous quail genomic sequence (Lindquester et ah, 1989). These are at identical amino acid positions as for the product of the p gene (Libri et ah, 1989 Forry-Shardies et al., 1990). 

In addition to the nonpolar interactions involving a and d positions of both chains, ionic interactions undoubtedly play a role in the stabilization of the structure. Thus, for example, a high proportion of residues occupying positions e are Glu residues whereas g positions are often basic in nature. In the coiled-coil with 

TABLE I Amino Acid Sequences of Alternatively Spliced Exons in Chicken a and P TM Genes as Expressed 

---

Hodges, R. S., Sodek, J., Smillie, L. B., and Jurasek, L. (1972). Tropomyosin Amino acid sequence and coiled-coil structure. Cold Spring Harh. Symp. Quant. Biol. 37, 299-310. 

V. AMINO ACID SEQUENCE AND COILED-COIL STRUCTURE... 

---