F-actin capping protein

In molecular biology, the F-actin capping protein is a protein which 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. The alpha subunit is a protein of about 268 to 286 amino acid residuesa and the beta subunit is approximately 280 aminop acids, their sequences are well conserved in eukaryotic species.

The actin filament system, a prominent part of the cytoskeleton in eukaryotic cells, is both a static structure and a dynamic network that can undergo rearrangements: it is thought to be involved in processes such as cell movement and phagocytosis, as well as muscle contraction.