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 overlapping but distinct expression patterns with other Xenopus laevis actins. In tailbud embryos, expressed in embryonic muscle (myotomes). In tadpoles, abundant in muscle from the tadpole tail with minor expression in the heart and limb buds. In adults, expressed mainly in skeletal muscle. Expressed from the end of gastrulation. 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. Due to the tetraploid nature of Xenopus laevis, each of these three alpha actin genes is present in at least two copies. 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.