Actin and neurofilament binding domain of brain spectrin beta subunit.
Tryptic digestion of brain spectrin generates a number of fragments from alpha and beta subunits; when these fragments are incubated with F-actin or neurofilament light subunit, four of them with molecular masses below 30 kDa sediment with the cytoskeleton structures. A selective purification of these fragments by ammonium sulfate fractionation and butyl-Sepharose chromatography has been achieved. Two fragments with molecular masses of 28 and 23 kDa bind to F-actin. Native brain spectrin causes half-maximal inhibition of the association at a concentration of 3 microM. Protein sequencing indicates that the actin-binding domain is contained in the beta subunit, in a stretch of amino acids at the N terminus from Ala43 (28-kDa fragment) or from Met104 (23-kDa fragment) and terminate probably at the C-terminal Lys288 or Lys284. Amino acids are numbered by reference to the sequence of the Drosophila beta subunit. The 28-kDa fragment also binds to the low-molecular-mass subunit of neurofilaments; brain spectrin heterodimer disrupts this binding. Hence, spectrin binds to F-actin and to neurofilaments via a common binding domain.
Frappier
T
T
Institut de Biologie Physico-Chimique, Centre National de la Recherche Scientifique, Paris, France.
Derancourt
J
J
Pradel
L A
LA
D000199:Actins / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001667:Binding, Competitive; D001921:Brain / Q000378:metabolism*; D002850:Chromatography, Gel; D004591:Electrophoresis, Polyacrylamide Gel; D004912:Erythrocytes / Q000378:metabolism; D006801:Humans; D007382:Intermediate Filaments / Q000378:metabolism*; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000378:metabolism; D013049:Spectrin / Q000235:genetics / Q000378:metabolism*; D013116:Spinal Cord / Q000378:metabolism; D013552:Swine; D014357:Trypsin
D000199:Actins; D010446:Peptide Fragments; D013049:Spectrin; D014357:Trypsin