Heterotrimeric Galphaq11 co-immunoprecipitates with surface-anchored GRP78 from plasma membranes of alpha2M*-stimulated macrophages.

Journal Article (Journal Article)

We have previously shown that a fraction of newly expressed GRP78 is translocated to the cell surface in association with the co-chaperone MTJ-1. Proteinase and methylamine-activated alpha(2)M (alpha(2)M*) bind to cell surface-associated GRP78 activating phosphoinositide-specific phospholipase C coupled to a pertussis toxin-insensitive heterotrimeric G protein, generating IP(3)/calcium signaling. We have now studied the association of pertussis toxin-insensitive Galphaq11, with GRP78/MTJ-1 complexes in the plasma membranes of alpha(2)M*-stimulated macrophages. When GRP78 was immunoprecipitated from plasma membranes of macrophages stimulated with alpha(2)M*, Galphaq11, and MTJ-1 were co-precipitated. Likewise Galphaq11 and GRP78 co-immunoprecipitated with MTJ-1 while GRP78 and MTJ-1 co-immunoprecipitated with Galphaq11. Silencing GRP78 expression with GRP78 dsRNA or MTJ-1 with MTJ-1 dsRNA greatly reduced the levels of Galphaq11 co-precipitated with GRP78 or MTJ-1. In conclusion, we show here that plasma membrane-associated GRP78 is coupled to pertussis toxin-insensitive Galphaq11 and forms a ternary signaling complex with MTJ-1.

Full Text

Duke Authors

Cited Authors

  • Misra, UK; Pizzo, SV

Published Date

  • May 1, 2008

Published In

Volume / Issue

  • 104 / 1

Start / End Page

  • 96 - 104

PubMed ID

  • 18213612

Electronic International Standard Serial Number (EISSN)

  • 1097-4644

Digital Object Identifier (DOI)

  • 10.1002/jcb.21607


  • eng

Conference Location

  • United States