Cleavage after lysine 32 in the Gγ2 subtype and after lysine 36 in the Gγ3 subtype of purified mixed brain Gβγ by endoproteinase Lys-C blocks Gβγ-mediated stimulation of phosphorylation of rhodopsin in urea-extracted rod outer segments by recombinant human β-adrenergic receptor kinase (hβARK1) holoenzyme while hβARK1 binding to rod outer segments is partially affected. This treatment does not attenuate the binding of the treated Gβγ to C-terminal fragments of hβARK1 containing the pleckstrin homology domain. Lys-C proteolysis also does not alter the association of the Gβγ with phospholipids, its ability to support pertussis toxin-catalyzed Gα(o)/Gα(i) ADP-ribosylation, or its ability to inhibit forskolin-stimulated platelet adenylate cyclase. The Gβ subunit remains noncovalently associated with the cleaved Gγ fragments. Thus, in addition to recruiting hβARK1 to its receptor substrate, Gγ contributes secondary and/or tertiary structural features to activate the kinase.
|Number of pages||8|
|Journal||Journal of Biological Chemistry|
|State||Published - Feb 9 1996|
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology