InterPro domain: IPR042489

The F-actin capping protein binds in a calcium-independent manner to the fast growing ends of actin filaments (barbed end) thereby blocking the exchange of subunits at these ends. Unlike gelsolin and severin this protein does not sever actin filaments. The F-actin capping protein is a heterodimer composed of two unrelated subunits: alpha and beta. Neither of the subunits shows sequence similarity to other filament-capping proteins [ 1 ].

This entry represent domain 1 found at the N terminus of the alpha subunit (CAPZA), which is a protein of about 268 to 286 amino acid residues whose sequence is well conserved in eukaryotic species [ 2 ]. In Drosophila mutations in the alpha and beta subunits cause actin accumulation and subsequent retinal degeneration [ 3 ]. In humans CAPZA is part of the WASH complex that controls the fission of endosomes [ 4 ].

1. Beta-actinin is equivalent to Cap Z protein. J. Biol. Chem. 265, 8712-5
2. Variant cDNAs encoding proteins similar to the alpha subunit of chicken CapZ. Cell Motil. Cytoskeleton 18, 204-14
3. Mutations in the Drosophila orthologs of the F-actin capping protein alpha- and beta-subunits cause actin accumulation and subsequent retinal degeneration. Genetics 171, 1757-65
4. The Arp2/3 activator WASH controls the fission of endosomes through a large multiprotein complex. Dev. Cell 17, 712-23