PDBsum entry 1s4x

Cell adhesion

PDB id: 1s4x

Contents

Protein chain

47 a.a. *

* Residue conservation analysis

PDB id:

1s4x

Name:

Cell adhesion

Title:

Nmr structure of the integrin b3 cytoplasmic domain in dpc micelles

Structure:

Integrin beta-3. Chain: a. Fragment: cytoplasmic domain (residues 742-788). Synonym: platelet membrane glycoprotein iiia, gpiiia, cd61 antigen. Engineered: yes

Source:

Homo sapiens. Human. Organism_taxid: 9606. Gene: itgb3, gp3a. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.

NMR struc:

20 models

Authors:

O.Vinogradova,J.Vaynberg,X.Kong,T.A.Haas,E.F.Plow,J.Qin

Key ref:

O.Vinogradova et al. (2004). Membrane-mediated structural transitions at the cytoplasmic face during integrin activation. Proc Natl Acad Sci U S A, 101, 4094-4099. PubMed id: 15024114 DOI: 10.1073/pnas.0400742101

Date:

19-Jan-04 Release date: 09-Mar-04

Protein chain

P05106  (ITB3_HUMAN) -  Integrin beta-3 from Homo sapiens

Seq: 788 a.a.

Struc: 47 a.a.

Enzyme reactions

• Enzyme class: E.C.?

DOI no: 10.1073/pnas.0400742101

Proc Natl Acad Sci U S A 101:4094-4099 (2004)

PubMed id: 15024114

Membrane-mediated structural transitions at the cytoplasmic face during integrin activation.

O.Vinogradova, J.Vaynberg, X.Kong, T.A.Haas, E.F.Plow, J.Qin.

ABSTRACT

Cytoplasmic face-mediated integrin inside-out activation remains a paradigm in transmembrane signal transduction. Emerging evidence suggests that this process involves dissociation of the complex between the integrin cytoplasmic tails; however, a dynamic image of how it occurs on the membrane surface remains elusive. We show here that, whereas membrane-proximal helices of integrin alpha/beta cytoplasmic tails associate in cytoplasm-like aqueous medium, they become partially embedded into membrane-mimetic micelles when unclasped. Membrane embedding induces substantial structural changes of the cytoplasmic tails as compared to their aqueous conformations and suggests there may be an upward movement of the membrane-proximal helices into the membrane during their separation. We further demonstrate that the beta3 tail exhibits additional membrane binding site at its C terminus containing the NPLY motif. Talin, a key intracellular integrin activator, recognizes this site as well as the membrane-proximal helix, thereby promoting cytoplasmic tail separation along the membrane surface. These data provide a structural basis of membrane-mediated changes at the cytoplasmic face in regulating integrin activation and signaling.

Selected figure(s)

Figure 2.
Fig. 2. Spectral perturbation for IIb/DPC and 3/DPC interactions. (A) Heteronuclear single quantum correlation (HSQC) spectra of 15N-labeled IIb in the absence (black) and presence (red) of 300 mM DPC showing dramatic perturbation in the membrane-proximal region K989-R997. (B) HSQC spectra of 15N-labeled 3 in the absence (black) and presence (red) of 300 mM DPC. A global spectral perturbation occurs indicating a complex structural rearrangement as compared to IIb in A.

Figure 5.
Fig. 5. Structural illustration of integrin activation by talin. (A) A model for membrane-mediated change of cytoplasmic face during integrin activation. Agonist stimulation induces a conformational change in talin that exposes its head domain (Talin-H). Talin-H binds to the [3] tail at both the NPLY-containing region and the membrane-proximal helix. The binding to the membrane-proximal region displaces the [IIb] tail from its complex with the [3] tail, leading to an unclasping, and the binding in the NPLY region releases a membrane-anchoring constraint on 3, which further facilitates the unclasping movement along the membrane surface. Notice the shifted membrane interface for both membrane-proximal helices before and after unclasping (green bars), which suggests a "fanning-out" unclasping process because the transmembrane domains may also undergo separation or open-scissor motion. The unclasping initiates the opening of the integrin C-terminal stalks, which is necessary for the rearrangement of the extracellular headpiece for high-affinity ligand binding. (B) HSQC spectra of the 15N-labeled 3 tail in the absence (black) and presence (red) of unlabeled talin F2-F3 at 35°C. Residues with significant chemical shift changes were labeled, which primarily involve membrane-proximal T720-D723 and C-terminal A735-A750, containing the N744-Y747 turn. (C) Surface plasmon resonance data. One hundred nanomol of talin-H (1-429) was passed over CM5 sensor chips coated with [3] (716-762) (red), a [3] membrane-proximal mutant (H722A/D723A, black), or a [3] single mutant (F730A, green), with association and dissociation phases of 360 sec. The former mutant had diminished binding to talin, but the latter has about the same as the binding capacity to talin, indicating that H722D723 is critical for talin binding. D723A/R724A mutations also had the same effect as H722A/D723A (data not shown). Talin-H made no detectable interaction with [IIb](989-1008) when this peptide was coupled to a CM5 chip.

Figures were selected by an automated process.