Gβ5γ2 Is a Highly Selective Activator of Phospholipid-dependent Enzymes

Maier, Udo; Бабич, А. А.; Macrez, Nathalie; Leopoldt, Daniela; Gierschik, Peter; Illenberger, Daria; Nürnberg, Bernd

doi:10.1074/jbc.275.18.13746

Cited by 73 publications

(57 citation statements)

References 67 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Moreover, both G␤␥-stimulated p110␥ autophosphorylation of the His-p110␥/ p101 heterodimer (EC 50 ϭ 30 nM) and lipid kinase activity (EC 50 ϭ 10 nM) were comparable with the data obtained with the GST-p101/p110␥ heterodimer (see Fig. 5B) (11,12). Taken together, these results clearly demonstrate that, in contrast to class I A PI3K␤, autophosphorylation of PI3K␥ is sensitive to G␤␥.…”

Section: Resultssupporting

confidence: 84%

“…These findings suggest a role for PI3K␥ autophosphorylation different from the class I A PI3K isoforms. Our observation that G␤␥ stimulates p110␥ autophosphorylation further supports this assumption (11,12). Since others have reported an inhibitory effect of G␤␥ on PI3K␥ protein kinase activity (29), we reexamined G␤␥-induced p110␥ autophosphorylation using recombinant purified protein (Fig.…”

Section: Resultssupporting

confidence: 81%

“…Although serine 1101 was not resolved in this structure it is clear from the data that it should be just beyond the C-terminal helix k␣ 12 , which lines the PtdIns-4,5-P 2 binding pocket. Therefore, from a sterical point of view, a preferential phosphorylation of this serine appears reasonable.…”

Section: Discussionmentioning

confidence: 83%

See 2 more Smart Citations

Identification and Characterization of the Autophosphorylation Sites of Phosphoinositide 3-Kinase Isoforms β and γ

Czupalla¹,

Culo²,

Müller³

et al. 2003

Journal of Biological Chemistry

Self Cite

View full text Add to dashboard Cite

Class I phosphoinositide 3-kinases (PI3Ks) are bifunctional enzymes possessing lipid kinase activity and the capacity to phosphorylate their catalytic and/or regulatory subunits. In this study, in vitro autophosphorylation of the G protein-sensitive p85-coupled class I A PI3K␤ and p101-coupled class I B PI3K␥ was examined. Autophosphorylation sites of both PI3K isoforms were mapped to Cterminal serine residues of the catalytic p110 subunit (i.e. serine 1070 of p110␤ and serine 1101 of p110␥). Like other class I A PI3K isoforms, autophosphorylation of p110␤ resulted in down-regulated PI3K␤ lipid kinase activity. However, no inhibitory effect of p110␥ autophosphorylation on PI3K␥ lipid kinase activity was observed. Moreover, PI3K␤ and PI3K␥ differed in the regulation of their autophosphorylation. Whereas p110␤ autophosphorylation was stimulated neither by G␤␥ complexes nor by a phosphotyrosyl peptide derived from the platelet-derived growth factor receptor, autophosphorylation of p110␥ was significantly enhanced by G␤␥ in a time-and concentration-dependent manner. In summary, we show that autophosphorylation of both PI3K␤ and PI3K␥ occurs in a C-terminal region of the catalytic p110 subunit but differs in its regulation and possible functional consequences, suggesting distinct roles of autophosphorylation of PI3K␤ and PI3K␥.Class I phosphoinositide 3-kinases (PI3Ks) 1 are lipid kinases that are activated in response to a variety of extracellular stimuli including hormones, neurotransmitters, and growth factors, which act via G protein-coupled receptors or receptor tyrosine kinases. These lipid kinases phosphorylate the D3 position of the inositol ring of phosphoinositides, thus generating intracellular lipid second messengers (1, 2). PtdIns, PtdIns-4-P, and PtdIns-4,5-P 2 are in vitro substrates of class I PI3Ks, although these enzymes predominantly produce PtdIns-3,4,5-P 3 in vivo. Class I PI3K lipid products transmit signals by recruiting intracellular effector molecules to the membrane, which contain particular pleckstrin homology domain modules. Effectors include serine/threonine kinases like Akt/protein kinase B, Tec family tyrosine kinases, and guanine nucleotide exchange factors for monomeric GTP-binding proteins like Grp1 and Vav (3). Consequently, class I PI3Ks are involved in the regulation of a wide variety of cellular functions such as differentiation, proliferation, survival, migration, and metabolism (4, 5).All class I PI3Ks are heterodimers consisting of a p110 catalytic and a p85 or p101 type regulatory subunit. According to the type of their associated regulatory subunit, class I PI3Ks can be further distinguished. The class I A catalytic p110␣, -␤, and -␦ subunits complex with adaptor molecules containing two Src homology 2 domains, of which p85 is the prototype. Through interaction of the adaptor Src homology 2 domains with phosphotyrosines, class I A PI3Ks are activated by receptor tyrosine kinases. In contrast, the only class I B member, p110␥, associates with a p101 regulatory subunit and is ...

show abstract

Section: Resultssupporting

confidence: 84%

Section: Resultssupporting

confidence: 81%

See 1 more Smart Citation

Identification and Characterization of the Autophosphorylation Sites of Phosphoinositide 3-Kinase Isoforms β and γ

Czupalla¹,

Culo²,

Müller³

et al. 2003

Journal of Biological Chemistry

Self Cite

View full text Add to dashboard Cite

show abstract

“…However, an almost perfect fit between the simulations and empirical data for both GRK2-ct and RACK1 can be achieved when either the affinities of G␤1␥2 for RACK1 and GRK2-ct are set to be twofold lower (200 and 1040 nM, respectively), or the affinity of G␤1␥2 for PI3K␥ is set to be twofold higher (2.8 nM; Supplementary Figure S2, B and C). Because these values are well within the range of variations reported for each parameter in the literature (Pumiglia et al, 1995;Maier et al, 1999;Maier et al, 2000;Kerchner et al, 2004;Chen et al, 2005), this indicates that the experimental data we obtained for both GRK2-ct and RACK1 are comparable to the theoretical predictions. Taken together, these results indicate that like GRK2-ct, RACK1 regulates PI3K␥ activity by competitive binding to G␤␥.…”

Section: Rack1 Inhibits G␤␥-induced Pi3k␥ Activation By Steric Hindrancesupporting

confidence: 73%

RACK1 Regulates Directional Cell Migration by Acting on Gβγ at the Interface with Its Effectors PLCβ and PI3Kγ

Chen

Lin

Shin

et al. 2008

MBoC

View full text Add to dashboard Cite

Migration of cells up the chemoattractant gradients is mediated by the binding of chemoattractants to G protein-coupled receptors and activation of a network of coordinated excitatory and inhibitory signals. Although the excitatory process has been well studied, the molecular nature of the inhibitory signals remains largely elusive. Here we report that the receptor for activated C kinase 1 (RACK1), a novel binding protein of heterotrimeric G protein ␤␥ (G␤␥) subunits, acts as a negative regulator of directed cell migration. After chemoattractant-induced polarization of Jurkat and neutrophil-like differentiated HL60 (dHL60) cells, RACK1 interacts with G␤␥ and is recruited to the leading edge. Down-regulation of RACK1 dramatically enhances chemotaxis of cells, whereas overexpression of RACK1 or a fragment of RACK1 that retains G␤␥-binding capacity inhibits cell migration. Further studies reveal that RACK1 does not modulate cell migration through binding to other known interacting proteins such as PKC␤ and Src. Rather, RACK1 selectively inhibits G␤␥-stimulated phosphatidylinositol 3-kinase ␥ (PI3K␥) and phospholipase C (PLC) ␤ activity, due to the competitive binding of RACK1, PI3K␥, and PLC␤ to G␤␥. Taken together, these findings provide a novel mechanism of regulating cell migration, i.e., RACK1-mediated interference with G␤␥-dependent activation of key effectors critical for chemotaxis.

show abstract

“…The Gb-subunits also play a role in determining speci®city. Gb 1 g 2 , Gb 2 g 2 , Gb 3 g 2 all stimulate PI3Kg with similar e cacy, but Gb 5 g 2 does not activate PI3Kg (Maier et al, 2000).…”

Section: Activation Of Pi3k By Gbg-dimersmentioning

confidence: 99%