PDBsum entry 1b9x

Signaling protein

PDB id: 1b9x

Contents

Protein chains

340 a.a. *

68 a.a. *

169 a.a. *

Metals

_GD ×6

Waters ×18

* Residue conservation analysis

PDB id:

1b9x

Name:

Signaling protein

Title:

Structural analysis of phosducin and its phosphorylation-regulated interaction with transducin

Structure:

Protein (transducin). Chain: a. Fragment: lys-c resistant fragment, the beta subunit. Synonym: gt beta. Protein (transducin). Chain: b. Fragment: lys-c resistant fragment, the gamma subunit cleaved after residue 68. Synonym: gt gamma.

Source:

Bos taurus. Cattle. Organism_taxid: 9913. Organ: eye. Tissue: retina. Cellular_location: rod outer segments. Other_details: purified from bovine rod outer segments. Rattus norvegicus. Norway rat.

Biol. unit:

Trimer (from PQS)

Resolution:

3.00Å R-factor: 0.217 R-free: 0.261

Authors:

R.Gaudet,P.B.Sigler

Key ref:

R.Gaudet et al. (1999). A molecular mechanism for the phosphorylation-dependent regulation of heterotrimeric G proteins by phosducin. Mol Cell, 3, 649-660. PubMed id: 10360181 DOI: 10.1016/S1097-2765(00)80358-5

Date:

16-Feb-99 Release date: 23-Feb-99

Protein chain

P62871  (GBB1_BOVIN) -  Guanine nucleotide-binding protein G(I)/G(S)/G(T) subunit beta-1 from Bos taurus

Seq: 340 a.a.

Struc: 340 a.a.*

Protein chain

P02698  (GBG1_BOVIN) -  Guanine nucleotide-binding protein G(T) subunit gamma-T1 from Bos taurus

Seq: 74 a.a.

Struc: 68 a.a.

Protein chain

P20942  (PHOS_RAT) -  Phosducin from Rattus norvegicus

Seq: 246 a.a.

Struc: 169 a.a.

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

DOI no: 10.1016/S1097-2765(00)80358-5

Mol Cell 3:649-660 (1999)

PubMed id: 10360181

A molecular mechanism for the phosphorylation-dependent regulation of heterotrimeric G proteins by phosducin.

R.Gaudet, J.R.Savage, J.N.McLaughlin, B.M.Willardson, P.B.Sigler.

ABSTRACT

Visual signal transduction is a nearly noise-free process that is exquisitely well regulated over a wide dynamic range of light intensity. A key component in dark/light adaptation is phosducin, a phosphorylatable protein that modulates the amount of transducin heterotrimer (Gt alpha beta gamma) available through sequestration of the beta gamma subunits (Gt beta gamma). The structure of the phosphophosducin/Gt beta gamma complex combined with mutational and biophysical analysis provides a stereochemical mechanism for the regulation of the phosducin-Gt beta gamma interaction. Phosphorylation of serine 73 causes an order-to-disorder transition of a 20-residue stretch, including the phosphorylation site, by disrupting a helix-capping motif. This transition disrupts phosducin's interface with Gt beta gamma, leading to the release of unencumbered Gt beta gamma, which reassociates with the membrane and Gt alpha to form a signaling-competent Gt alpha beta gamma heterotrimer.

Selected figure(s)

Figure 4.
Figure 4. One-Dimensional Proton NMR of the N-Terminal Domain(A and C) Amide region.(B and D) Methylene region.The spectrum of the phosphorylated N-terminal domain is shown at the top (A and B) and that of the unphosphorylated N-terminal domain is at the bottom (C and D). Arrows point to spectral features that differ between the two forms of the domain.

Figure 6.
Figure 6. Interactions of Phospho-Phosducin and G[t]α with G[t]βγ(A) Ribbon diagram of the phosducin/G[t]βγ complex where residues 67–86, which become disordered upon Ser-73 phosphorylation, are colored cyan. The N-terminal domain of phosducin is purple, with its 30-residue flexible loop in green. The C-terminal domain is blue. G[t]β is gold, and G[t]γ is silver.(B) The transducin heterotrimer ([14]) with G[t]α in red, the GDP in black, and G[t]βγ colored as in (A). Residues 67–86 in phosducin overlap the G[t]α-G[t]βγ interaction surface.(C) Ribbon diagram (stereo pair) of the phosducin/G[t]βγ interface near Helix 2. Residues involved in the interactions with phosducin segment from Arg-67 to Asp-86 are shown in ball-and-stick representations. Phosducin residues are labeled with purple or cyan symbols, and G[t]βγ residues with black symbols. The complex is viewed in the same “top” orientation in all three panels.

The above figures are reprinted by permission from Cell Press: Mol Cell (1999, 3, 649-660) copyright 1999.

Figures were selected by an automated process.