N-terminal actin binding

N-terminal actin-binding domains and in the spectrin repeats that form the rod domains (Davison and Critchley, 1988). The spectrin repeats are found in distinct multiples in each protein, resulting in a characteristic actin crosslinking distance. a-Actinin contains four repeats, /3-spectrin contains 17, a-spectrin contains 20, and dystrophin contains 24. The sequences of some spectrin repeats of a- and /3-spectrin are similar in many ways to the four repeats present in a-actinin (Dubreuil, 1991). Within the cell, a-actinin and spectrin dimerize, although the spectrins interact further to generate a functional tetramer (Fig. 1). Most notable is that the ends of the native spectrin tetramer involved in the dimerization event show remarkable similarity to the rod domain repeats of a-actinin that also mediate dimer formation. 

Bryan, J., and S. Hwo. 1986. Definition of an N-terminal actin-binding domain and a C-terminal Ca2+ regulatory domain in human brevin. J Cell Biol. 102 1439—46. 

Alpha-Actinin is a rod-like (3-4 nmx 30-40 nm) cytoskeletal protein belonging to the same family as spectrin, dystrophin and utrophin. a-Actinin is a homodimer with a subunit molecular weight of 94-103 kDa in which the subunits are antiparallel in orientation. The molecule can be devised into three domains, an N-terminal actin binding domain (approximately residues 1-245), four internal 120 residue repeats, and a C-terminal region containing two EF-hand Ca -binding motifs (Baron et al. 1987, Blanchard et al. 1989). Apart from actin, a-actinin has been reported to bind to the cytoskel-... 

Wang Z, Jiang H, Yang ZQ, Chacko S (1997) Both N-terminal myosin-binding and C-terminal actin-binding sites on smooth muscle caldesmon are required for cal-desmon-mediated inhibition of actin filament velocity. Proc Nad Acad Sci U S A 94 11899-11904... 

Figure 14.15 Stmcture of the SI fragment of chicken myosin as a Richardson diagram (a) and a space-filling model (b). The two light chains are shown in magenta and yellow. The heavy chain is colored according to three proteolytic fragments produced by trypsin a 25-kDa N-terminal domain (green) a central 50-kDa fragment (red) divided by a cleft into a 50K upper and a 50K lower domain and a 20-kDa C-terminal domain (blue) that links the myosin head to the coiled-coil tail. The 50-kDa and 20-kDa domains both bind actin, while the 25-kDa domain binds ATP. [(b) Courtesy of 1. Rayment.]...

The three selectins are related both structurally and functionally. They are transmembrane proteins, with an N-terminal C-type actin domain, followed by an EGF repeat and a variable number of complement control protein (CCP) domains. Selectins bind carbohydrates, which are present in various glycoproteins. 

Figure 10.7 The EGF receptor. The N-terminal, extracellular region of the receptor contains 622 amino acids. It displays two cysteine-rich regions, between which the ligand-binding domain is located. A 23 amino acid hydrophobic domain spans the plasma membrane. The receptor cytoplasmic region contains some 542 amino acids. It displays a tyrosine kinase domain, which includes several tyrosine autophosphorylation sites, and an actin-binding domain that may facilitate interaction with the cell cytoskeleton...

How does actin bind The actin monomer consists of four subdomains, 1, 2, 3, and 4 numbered from the N terminus (Fig. 7-10). The negatively charged N-terminal region of actin contains the sequence... 

Within the N-terminal, ABDs of three actin-binding sites (ABS) from spectrin superfamily proteins have been delineated (ABS1, ABS2, and ABS3). The first and third ABS have been localized to the al helix in... 

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