TABLE 4.

Comparison of mutant actins and pY53-actins with Y/Y-actin

Symbols are as follows. ↔, similar to WT; ↓, slightly less than WT; ↓↓, much less than WT; ↑, slightly more than WT; ↑↑, much more than WT; ND, not determined; NA, not applicable because pY53-actin is not present during growth and appears only after 12 h into development.

Property	Y/F	Y/W	Y/L	Y/A	Y/E	pY53a
DNase I inhibition	↔	ND	ND	↓↓	↓↓	↓↓
Polymerization rate	↔	↔	↓	↓↓	↓↓	↓↓
Critical concentration	↔	↔	↔	↑↑	↑↑	↑↑
Filament length	↔	↔	↔	↓↓	↓↓	↓↓
ATP exchange rate	↔	↑↑	↑↑	↑↑	↑↑	↓↓
Actomyosin ATPase	↔	ND	ND	↔b	↔b	↔
In vitro motility	↔	ND	ND	↔	↔	ND
Cell growth	↔	↓	↓	↓	↔c	NA
Development	↔	↔	↔	↓↓	↓c	NA

^a Data for pY53-actin are from Liu et al. (10) and Baek et al. (14).

^b Filaments stabilized with phalloidin.

^c Phenotypic effects may have been low because of low expression of Y/E (Figs. 9 and 10A).