Brain spectrin and friends

Brain spectrin (fodrin, calspectin), is an actin binding protein, and composed of two α- and two β-subunits which combine by head-to-head interaction to a heterotetramere. Together with other proteins it forms a proteinaceous meshwork underlying the cytoplasmic surface of the plasma membrane. In the mammalian brain, three forms of spectrins were identified, an axonal, a somatodendritic and a astroglial one. A subcellular localization at the electron microscopic-level suggests that these forms are not only attached to membranes but expand into the cytoplasm. It was shown that they differ in their subcellular distribution, and their temporal appearance during postnatal brain development. The subplasmalemmal cytoskeleton is composed of brain spectrin and a variety of proteins such as actin and calmodulin, and we discuss here two additional proteins, F1 and parvalbumin, which may bind to brain spectrin and may have to be included in the circle of proteins interacting with brain spectrin.