Spectrin is the major molecular constituent of the red cell membrane skeleton. We have isolated overlapping human erythroid β-spectrin cDNA clones and determined 6773 base pairs of contiguous nucleotide sequence. This includes the entire coding sequence of β-spectrin. The sequence translates into a 2137 amino acid, 246-kDa peptide. β-Spectrin is found to consist of three distinct domains. Domain I, at the N terminus, is a 272-amino acid region lacking resemblance to the spectrin repetitive motif. Sequences in this region exhibit striking sequence homology, at both nucleotide and amino acid levels, to the N-terminal 'actin-binding' domains of α-actinin and dystrophin. Between residues 51 and 270 there is 55% amino acid identity to human dystrophin, with only four single amino acid gaps in alignment. Domain II consists of 17 spectrin repeats. Several sequence variations are oberved in typical repeat structure. Homology to α-actinin extends beyond domain I into the N-terminal portion of domain II. Domain III, 52 amino acid residues at the C terminus, does not adhere to the spectrin repeat motif. Combining knowledge of spectrin primary structure with previously reported functional studies, it is possible to make several inferenmces regarding structure/function relationships within the β-spectrin molecule.
|Original language||English (US)|
|Number of pages||6|
|Journal||Journal of Biological Chemistry|
|State||Published - Aug 3 1990|
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology