Sophisticated regulation of the actin cytoskeleton by a variety of
actin-binding proteins is essential for eukaryotic cells to perform their diverse functions. The
plastin (also know, as
fimbrin)
protein family belongs to actin-bundling
proteins, and the
protein family is evolutionarily conserved and expressed in yeast, plant, and animal cells. Plastins are characterized by EF-hand Ca(2+)-binding domains and actin-binding domains and can cross-link actin filaments into higher-order assemblies like bundles. Three
isoforms have been identified in mammals.
T-plastin is expressed in cells from solid tissues, such as neurons in the brain.
I-plastin expression is restricted to intestine and kidney; the
isoform plays a vital role in the function of absorptive epithelia in these organs.
L-plastin is expressed in hematopoietic cell lineages and in many types of
cancer cells; the
isoform is thus considered to be a useful
biomarker for
cancer.