Spectrin Beta, Erythrocytic (SPTb)

SPTb encodes a member of the spectrin gene family. Spectrin proteins, along with ankyrin, play a role in cell membrane organization and stability. The protein encoded by this locus functions in stability of erythrocyte membranes, and mutations in this gene have been associated with spherocytosis type 2, hereditary elliptocytosis, and neonatal hemolytic anemia. The sequence encodes a 2,137-amino acid, 246-kD protein, consisting of 3 domains: domain I, at the N-terminus, is a 272-amino acid region lacking resemblance to the spectrin repetitive motif but showing striking homology at both nucleotide and amino acid levels to the N-terminal 'actin-binding' domains of alpha-actinin and dystrophin; domain II consists of 17 spectrin repeats; and domain III, 52 amino acid residues at the C terminus, does not adhere to the spectrin repeat motif.