The complete sequence of Drosophila beta-spectrin reveals supra-motifs comprising eight 106-residue segments.

AUTOR(ES)

Byers, T J

RESUMO

The alpha and beta chains of spectrin are homologous, yet they have acquired different structural features that work in synergy to give the multimer its overall properties. The primary amino acid sequence of each spectrin subunit is dominated by tandemly repeated 106-residue motifs. By comparing the complete Drosophila beta-spectrin sequence with other spectrins we have discovered evidence that a higher-order, 848-amino acid supra-motif is tandemly repeated in both alpha- and beta-spectrin. These data argue that alpha- and beta-spectrin, rather than evolving independently from sequences encoding the ancestral 106-residue motifs, must have arisen after the establishment of a large supra-motif composed of eight of the 106-residue motifs. Our data suggest the segment structure of a progenitor gene that gave rise to both alpha- and beta-spectrin as well as dystrophin. The structural differences that evolved after the split between the alpha- and beta-spectrin genes confer the independent functions that exist in their products today.

Documentos Relacionados

• Ankyrin and beta-spectrin accumulate independently of alpha-spectrin in Drosophila.
• Recurrent fatal hydrops fetalis associated with a nucleotide substitution in the erythrocyte beta-spectrin gene.
• Point mutation in the beta-spectrin gene associated with alpha I/74 hereditary elliptocytosis. Implications for the mechanism of spectrin dimer self-association.
• The sequence of the human immunoglobulin mu-delta intron reveals possible vestigial switch segments.
• Isolation and characterization of cDNA clones for human erythrocyte beta-spectrin.