Fascin

Fascin is an actin cross-linking protein.

It is a 54-58 kilodalton monomeric actin filament bundling protein originally isolated from sea urchin egg but also found in Drosophila and vertebrates, including humans. Fascin (from the Latin for bundle) is spaced at 11 nanometre intervals along the filament. The bundles in cross section are seen to be hexagonally packed, and the longitudinal spacing is compatible with a model where fascin cross-links at alternating 4 and 5 actins. It is calcium insensitive and monomeric. Three forms of fascin are found in vertebrates: Fascin1, widely found in the nervous system and elsewhere; fascin2 found in the retinal photoreceptor cells; fascin3, which is only found in the testes.