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

Published

Journal Article

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.

Full Text

Duke Authors

Cited Authors

  • Hu, RJ; Bennett, V

Published Date

  • September 25, 1991

Published In

Volume / Issue

  • 266 / 27

Start / End Page

  • 18200 - 18205

PubMed ID

  • 1833394

Pubmed Central ID

  • 1833394

International Standard Serial Number (ISSN)

  • 0021-9258

Language

  • eng

Conference Location

  • United States