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.
Dipartimento di Biologia Molecolare, Università degli Studi di Siena, 53100 Siena, Italy.
Elisa
E
Ferro
David
D
Magrini
Paolo
P
Guazzi
Thomas H
TH
Fischer
Sara
S
Pistolesi
Rebecca
R
Pogni
Gilbert C
GC
White
Lorenza
L
Trabalzini
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