Membrane skeleton in α-adducin–null RBCs. The major membrane skeleton components α- and β-spectrin, ankyrin, band 3, proteins 4.1 and 4.2, and actin appear normal in α-adducin–null RBC ghost membranes by SDS-PAGE (A) and Western blotting (B). Other components of the junctional complex—p55, GPC, and protein 4.9 (dematin)—also appear normal. (C) The actin capping protein EcapZ is strikingly up-regulated in adducin-null RBC membranes. Tropomodulin (Tmod) appears normal. (D) TM is decreased to approximately 20% of normal in the absence of adducin. +/+ indicates wild-type; −/−, homozygous null.