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 actins. In tailbud embryos, expressed in embryonic muscle (myotomes). In adults, expressed exclusively in skeletal muscle. First expressed after neurulation (stage 18), and expressed throughout development. 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 promotes actin repolymerization. Monomethylation at Lys-86 (K84me1) regulates actin-myosin interaction and actomyosin-dependent processes. Demethylation by ALKBH4 is required for maintaining actomyosin dynamics supporting normal cleavage furrow ingression during cytokinesis and cell migration. 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. PubMed:3172214 suggest that the sequences isolated in PubMed:3009830 (alpha3-II) and PubMed:3172214 (alpha3-I) may represent paralogous genes in tetraploid Xenopus laevis. 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.