Publications [#112904] of G Vann V. Bennett

Papers Published

1. RJ Hu, V Bennett, In vitro proteolysis of brain spectrin by calpain I inhibits association of spectrin with ankyrin-independent membrane binding site(s)., The Journal of biological chemistry, UNITED STATES, vol. 266 no. 27 (September, 1991), pp. 18200-5, ISSN 0021-9258
   (last updated on 2003/02/18)

   Abstract:
   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.

   Keywords:
   Actins • Animals • Ankyrins • Binding Sites • Blood Proteins • Brain • Calpain • Cattle • Cell Membrane • Electrophoresis, Polyacrylamide Gel • Hydrolysis • Membrane Proteins • Microscopy, Electron • Spectrin • metabolism • metabolism* • ultrastructure