Actin structure‐function relationships in vitro using oligodeoxynucleotide‐directed site‐specific mutagenesis

Molecular genetics of actin function

“…Replacement of Asp-i 1 by non-acidic amino acids in a human askeletal muscle actin expressed in vitro prevented N-terminal processing, but in only one case did the actin have reduced ability to polymerize [29]. The lack of any polymerization effects of mutants at Asp-Il is surprising given their effect on protein conformation [155] and the involvement of this amino acid with of N-terminal processing in polymerization might arize from the use of heterologous or homologous actins for the copolymerizations in the different studies [32]. Since there is no biochemical evidence for a direct role of the N-terminus in polymerization, these effects probably arise from a conformational change which affects a distant actin-actin contact site.…”

Genetic Alteration of Proteins in Actin-Based Motility Systems

“…The discussion of these findings by Rubenstein et al (65) is noteworthy as a caveat against any unsophisticated interpretation of the consequences of single amino acid substitutions. The substitution of Asp-II appears to cause a fraction of the actin to fold in a pathway different from the usual one.…”

“…Inactivation of the actin gene in Saccharomyces cerevisiae is lethal, as is introduction of an extra copy of this gene (65). Replacement of the actin gene by mutated sequences makes it possible to study the structural requirements of actin functions within the context of the living cell and to identify proteins that interact with the actin.…”

Mutant actin: A dead end?

“…Protein engineering techniques have great potential for the study of muscle proteins (see reviews by Rubenstein et al, 1989;Atkinson & Stewart, 1991;Fyrberg et al, 1991;Sparrow et al, 1991). Mutated actins have been studied both in vitro (Solomon & Rubenstein, 1987;Solomon et al, 1988) and in vivo (Shortle et al, 1982;Mahaffey et al, 1985;Drummond et al, 1991) and these approaches have provided much useful information on the importance of individual amino acids for normal actin function.…”