Actins are highly conserved proteins that are involved in various types of cell motility. Polymerization of globular actin (G-actin) leads to a structural filament (F-actin) in the form of a two-stranded helix. Each actin can bind to 4 others. Shows a different expression pattern to Xenopus laevis act2. Expressed in stage 24 and 42 embryos as well as in adult heart, but not adult skeletal muscle. Oxidation of Met-46 and Met-49 by MICALs (mical1, mical2 or mical3) to form methionine sulfoxide promotes actin filament depolymerization. Mical1 and mical2 produce the (R)-S-oxide form. The (R)-S-oxide form is reverted by msrb1 and msrb2, which promote actin repolymerization (By similarity). Xenopus contains at least three sarcomeric alpha actin genes that are preferentially expressed in either heart or skeletal muscle. The cardiac versus skeletal expression patterns of actins are probably sequence-dependent. For example, cardiac actins contain a Glu at position 3 of the mature peptide, whereas skeletal actins contain an Asp at this position. Belongs to the actin family.