G-protein binding features and regulation of the RalGDS family member, RGL2.
RGL2 [RalGDS (Ral guanine nucleotide dissociation stimulator)-like 2] is a member of the RalGDS family that we have previously isolated and characterized as a potential effector for Ras and the Ras analogue Rap1b. The protein shares 89% sequence identity with its mouse orthologue Rlf (RalGDS-like factor). In the present study we further characterized the G-protein-binding features of RGL2 and also demonstrated that RGL2 has guanine-nucleotide-exchange activity toward the small GTPase RalA. We found that RGL2/Rlf properties are well conserved between human and mouse species. Both RGL2 and Rlf have a putative PKA (protein kinase A) phosphorylation site at the C-terminal of the domain that regulates the interaction with small GTPases. We demonstrated that RGL2 is phosphorylated by PKA and phosphorylation reduces the ability of RGL2 to bind H-Ras. As RGL2 and Rlf are unique in the RalGDS family in having a PKA site in the Ras-binding domain, the results of the present study indicate that Ras may distinguish between the different RalGDS family members by their phosphorylation by PKA.
Ferro
Elisa
E
Dipartimento di Biologia Molecolare, Università degli Studi di Siena, 53100 Siena, Italy.
Magrini
David
D
Guazzi
Paolo
P
Fischer
Thomas H
TH
Pistolesi
Sara
S
Pogni
Rebecca
R
White
Gilbert C
GC
Trabalzini
Lorenza
L
D000595:Amino Acid Sequence; D000818:Animals; D002478:Cells, Cultured; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D017353:Gene Deletion; D020662:Guanine Nucleotide Exchange Factors / Q000502:physiology; D006801:Humans; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D020559:Monomeric GTP-Binding Proteins / Q000378:metabolism; D010766:Phosphorylation; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D016415:Sequence Alignment; D013329:Structure-Activity Relationship; D014157:Transcription Factors / Q000737:chemistry; D020798:Two-Hybrid System Techniques; D020691:rab GTP-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D018631:ras Proteins / Q000378:metabolism
D020662:Guanine Nucleotide Exchange Factors; C102739:RGL2 protein, human; D011993:Recombinant Fusion Proteins; C490805:Rgl2 protein, mouse; D014157:Transcription Factors; D017868:Cyclic AMP-Dependent Protein Kinases; D020559:Monomeric GTP-Binding Proteins; D020691:rab GTP-Binding Proteins; D018631:ras Proteins