PDBsum entry: 1kjy

Signaling protein

PDB id: 1kjy

Contents

Protein chains

320 a.a. *

35 a.a. *

34 a.a. *

Ligands

GDP ×2

Metals

_MG ×2

_CS ×15

Waters ×206

* Residue conservation analysis

PDB id:

1kjy

Name:

Signaling protein

Title:

Crystal structure of human g[alpha]i1 bound to the goloco mo rgs14

Structure:

Guanine nucleotide-binding protein g(i), alpha-1 chain: a, c. Synonym: adenylate cyclase-inhibiting g alpha protein. Engineered: yes. Regulator of g-protein signaling 14. Chain: b, d. Synonym: rgs14. Engineered: yes

Source:

Homo sapiens. Human. Organism_taxid: 9606. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008. Synthetic: yes. Other_details: the peptide was chemically synthesized. The of the peptide is naturally found in rattus norvegicus (rat

Biol. unit:

Dimer (from PQS)

Resolution:

2.70Å R-factor: 0.238 R-free: 0.299

Authors:

R.J.Kimple,M.E.Kimple,L.Betts,J.Sondek,D.P.Siderovski

Key ref:

R.J.Kimple et al. (2002). Structural determinants for GoLoco-induced inhibition of nucleotide release by Galpha subunits. Nature, 416, 878-881. PubMed id: 11976690 DOI: 10.1038/416878a

Date:

05-Dec-01 Release date: 08-May-02

Protein chains

P63096  (GNAI1_HUMAN) -  Guanine nucleotide-binding protein G(i) subunit alpha-1

Seq: 354 a.a.

Struc: 320 a.a.*

Protein chain

O08773  (RGS14_RAT) -  Regulator of G-protein signaling 14

Seq: 544 a.a.

Struc: 35 a.a.

Protein chain

O08773  (RGS14_RAT) -  Regulator of G-protein signaling 14

Seq: 544 a.a.

Struc: 34 a.a.

* PDB and UniProt seqs differ at 1 residue position (black cross)

 Gene Ontology (GO) functional annotation 

• Cellular component: intracellular (11 terms)
• Biological process: cell cycle (9 terms)
• Biochemical function: nucleotide binding (12 terms)

DOI no: 10.1038/416878a

Nature 416:878-881 (2002)

PubMed id: 11976690

Structural determinants for GoLoco-induced inhibition of nucleotide release by Galpha subunits.

R.J.Kimple, M.E.Kimple, L.Betts, J.Sondek, D.P.Siderovski.

ABSTRACT

Heterotrimeric G-proteins bind to cell-surface receptors and are integral in transmission of signals from outside the cell. Upon activation of the Galpha subunit by binding of GTP, the Galpha and Gbetagamma subunits dissociate and interact with effector proteins for signal transduction. Regulatory proteins with the 19-amino-acid GoLoco motif can bind to Galpha subunits and maintain G-protein subunit dissociation in the absence of Galpha activation. Here we describe the structural determinants of GoLoco activity as revealed by the crystal structure of Galpha(i1) GDP bound to the GoLoco region of the 'regulator of G-protein signalling' protein RGS14. Key contacts are described between the GoLoco motif and Galpha protein, including the extension of GoLoco's highly conserved Asp/Glu-Gln-Arg triad into the nucleotide-binding pocket of Galpha to make direct contact with the GDP alpha- and beta-phosphates. The structural organization of the GoLoco Galpha(i1) complex, when combined with supporting data from domain-swapping experiments, suggests that the Galpha all-helical domain and GoLoco-region carboxy-terminal residues control the specificity of GoLoco Galpha interactions.

Selected figure(s)

Figure 1.
Figure 1: alpha-[i1] [glyph.gif]GDP in complex with the RGS14 GoLoco region. a, Ribbon drawing of R14GL peptide (red) in contact with the Ras-like (green) and all-helical (yellow) domains of G [i1]. Also shown are the three switch regions of G [i1] (blue), GDP (magenta) and Mg2+ (orange). b, Molecular surface of R14GL (red) and G (cyan) contacts on G [i1] GDP, denoting shared switch II residue contacts (magenta). Highlighted are G [i1] residues that contact the R14GL peptide and are different within G [o]. c, Space fill model of [i1] GDP in its R14GL-bound conformation (switch regions in blue, [148]alpha B - [149]alpha C loop in yellow) and G [150]beta [1] [151]gamma [2]-bound conformation (in cyan).

Figure 2.
Figure 2: Role of the GoLoco motif Asp-Gln-Arg triad in GDI activity. a, Stereo view of the remodelled nucleotide binding pocket. The G [i1] Arg 178 side chain (transparent yellow) is re-oriented (green) to form a salt bridge with Glu 43 of the G [i1] subunit, thus allowing Arg r516 of the GoLoco motif (red) to approach and interact with the - and -phosphate oxygens (and bridging oxygen) of GDP. b, GST -RGS14 GoLoco fusion proteins (GST -RGS14[496 -531]) bearing alanine (R516A) or leucine (R516L) substitutions show decreased GDI activity relative to the wild-type GST -RGS14[496 -531] (WT), as measured both by BODIPY -GTP S binding (left) and by AlF[4]^--induced increase of intrinsic tryptophan fluorescence (right).

The above figures are reprinted by permission from Macmillan Publishers Ltd: Nature (2002, 416, 878-881) copyright 2002.

Figures were selected by the author.