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In vitro proteolysis of brain spectrin by calpain I inhibits association of spectrin with ankyrin-independent membrane binding site(s).

Publication ,  Journal Article
Hu, RJ; Bennett, V
Published in: J Biol Chem
September 25, 1991

This report demonstrates that specific proteolysis of brain spectrin by a calcium-dependent protease, calpain I, abolishes association of brain spectrin with the ankyrin-independent binding site(s) in brain membranes. Calpain I cleaves the beta subunit of spectrin at the N-terminal end leaving a 218-kDa fragment and cleaves the alpha subunit in the midregion to produce 150- and 130-kDa fragments. Calpain-proteolyzed spectrin almost completely loses the capacity to displace binding of intact spectrin to membranes. Spectrin digested by calpain I under conditions that almost completely destroyed membrane-binding remained associated as a tetramer and retained about 60% of the ability to associate with actin filaments. Cleavage of spectrin occurred at sites distinct from the membrane-binding site which is located on the beta subunit since the isolated 218-kDa fragment of the beta subunit as well as a reconstituted complex of alpha and 218-kDa beta subunit fragment partially regained binding activity. Moreover, cleavage of the alpha subunit alone reduced the affinity of spectrin for membranes by 2-fold. A consequence of distinct sites for calpain I cleavage and membrane-binding is that calpain I can digest spectrin while spectrin is complexed with other proteins and therefore has the potential to mediate disassembly of a spectrin-actin network from membranes.

Duke Scholars

Published In

J Biol Chem

ISSN

0021-9258

Publication Date

September 25, 1991

Volume

266

Issue

27

Start / End Page

18200 / 18205

Location

United States

Related Subject Headings

  • Spectrin
  • Microscopy, Electron
  • Membrane Proteins
  • In Vitro Techniques
  • Hydrolysis
  • Electrophoresis, Polyacrylamide Gel
  • Cell Membrane
  • Cattle
  • Calpain
  • Brain
 

Published In

J Biol Chem

ISSN

0021-9258

Publication Date

September 25, 1991

Volume

266

Issue

27

Start / End Page

18200 / 18205

Location

United States

Related Subject Headings

  • Spectrin
  • Microscopy, Electron
  • Membrane Proteins
  • In Vitro Techniques
  • Hydrolysis
  • Electrophoresis, Polyacrylamide Gel
  • Cell Membrane
  • Cattle
  • Calpain
  • Brain