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. In tailbud embryos, expressed in embryonic muscle (myotomes). Unlike Xenopus laevis act3, expression is restricted to embryonic and tadpole stages. Not expressed in adults. 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 different 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; Xenopus 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.