Search results for "Motif"

Six amino acids define a minimal dimerization sequence and stabilize a transmembrane helix dimer by close packing and hydrogen bonding

2013

AbstractDistinct amino acid sequences have been described to mediate oligomerization of transmembrane α-helices. However, as the sequence context is crucial to determine specificity in transmembrane helix–helix interaction, the question arises how small a sequence can be without losing specificity. In the present analysis, six amino acids have been identified in the PsbF transmembrane helix dimer, which form the contact region of two interacting helices and are directly involved in helix–helix interactions. However, individual amino acids within the complex sequence pattern only together ensure sequence specificity of the analyzed transmembrane helix–helix interactions by mediating close pa…

β2 integrin phosphorylation on Thr758 acts as a molecular switch to regulate 14-3-3 and filamin binding

2008

AbstractLeukocyte integrins of the β2 family are essential for immune cell-cell adhesion. In activated cells, β2 integrins are phosphorylated on the cytoplasmic Thr758, leading to 14-3-3 protein recruitment to the β2 integrin. The mutation of this phosphorylation site impairs cell adhesion, actin reorganization, and cell spreading. Thr758 is contained in a Thr triplet of β2 that also mediates binding to filamin. Here, we investigated the binding of filamin, talin, and 14-3-3 proteins to phosphorylated and unphosphorylated β2 integrins by biochemical methods and x-ray crystallography. 14-3-3 proteins bound only to the phosphorylated integrin cytoplasmic peptide, with a high affinity (Kd, 261…

Concerted motions of the integrin-binding loop and the C-terminal tail of the non-RGD disintegrin obtustatin.

2003

Obtustatin is a potent and selective inhibitor of the alpha1beta1 integrin in vitro and of angiogenesis in vivo. It possesses an integrin recognition loop that harbors, in a lateral position, the inhibitory 21KTS23 motif. We report an analysis of the dynamics of the backbone and side-chain atoms of obtustatin by homonuclear NMR methods. Angular mobility has been calculated for 90 assigned cross-peaks from 22 off-resonance rotating frame nuclear Overhauser effect spectroscopy spectra recorded at three magnetic fields. Our results suggest that the integrin binding loop and the C-terminal tail display concerted motions, which can be interpreted by hinge effects. Among the integrin-binding moti…

Mona/Gads SH3C binding to hematopoietic progenitor kinase 1 (HPK1) combines an atypical SH3 binding motif, R/KXXK, with a classical PXXP motif embedd…

2004

Hematopoietic progenitor kinase 1 (HPK1) is implicated in signaling downstream of the T cell receptor. Its non-catalytic, C-terminal half contains several prolinerich motifs, which have been shown to interact with different SH3 domain-containing adaptor proteins in vitro. One of these, Mona/Gads, was also shown to bind HPK1 in mouse T cells in vivo. The region of HPK1 that binds to the Mona/Gads C-terminal SH3 domain has been mapped and shows only very limited similarity to a recently identified high affinity binding motif in SLP-76, another T-cell adaptor. Using isothermal titration calorimetry and x-ray crystallography, the binding of the HPK1 motif to Mona/Gads SH3C has now been characte…

Structure of the human filamin A actin-binding domain.

2009

Filamin A (FLNa) is a large dimeric protein that binds to actin filaments via its actin-binding domain (ABD). The crystal structure of this domain was solved at 3.2 A resolution. The domain adopts a closed conformation typical of other ABDs, but also forms a dimer both in crystallization conditions and in solution. The structure shows the localization of the residues mutated in patients with periventricular nodular heterotopia or otopalatodigital syndrome. Structural analysis predicts that mutations in both types of disorder may affect actin binding.

Interaction of Circadian Clock Proteins CRY1 and PER2 Is Modulated by Zinc Binding and Disulfide Bond Formation

2014

SummaryPeriod (PER) proteins are essential components of the mammalian circadian clock. They form complexes with cryptochromes (CRY), which negatively regulate CLOCK/BMAL1-dependent transactivation of clock and clock-controlled genes. To define the roles of mammalian CRY/PER complexes in the circadian clock, we have determined the crystal structure of a complex comprising the photolyase homology region of mouse CRY1 (mCRY1) and a C-terminal mouse PER2 (mPER2) fragment. mPER2 winds around the helical mCRY1 domain covering the binding sites of FBXL3 and CLOCK/BMAL1, but not the FAD binding pocket. Our structure revealed an unexpected zinc ion in one interface, which stabilizes mCRY1-mPER2 int…

The C-terminal rod 2 fragment of filamin A forms a compact structure that can be extended

2012

Filamins are large proteins that cross-link actin filaments and connect to other cellular components. The C-terminal rod 2 region of FLNa (filamin A) mediates dimerization and interacts with several transmembrane receptors and intracellular signalling adaptors. SAXS (small-angle X-ray scattering) experiments were used to make a model of a six immunoglobulin-like domain fragment of the FLNa rod 2 (domains 16–21). This fragment had a surprising three-branched structural arrangement, where each branch was made of a tightly packed two-domain pair. Peptides derived from transmembrane receptors and intracellular signalling proteins induced a more open structure of the six domain fragment. Mutagen…

Derivazione Efficiente di Pattern Strutturati Frequenti da Database di Natura Biologica

2004

Optimal extraction of motif patterns in 2D

2009

The combinatorial explosion of motif patterns occurring in 1D and 2D arrays leads to the consideration of special classes of motifs growing linearly with the size of the input array. Such motifs, called irredundant motifs, are able to succinctly represent all of the other motifs occurring in the same array within reasonable time and space bounds. In previous work irredundant motifs were extracted from 2D arrays in O (N 2 log 2 n log log n) and O (N 3) time, where N is the size of the 2D input array and n is its largest dimension. In this paper, we present an algorithm to extract irredundant motifs from 2D arrays that is quadratic in the size of the input. The input is defined on a binary al…

L'abandon sportif : des motifs d'abandon aux modèles théoriques : une recherche longitudinale chez les handballeuses et les basketteuses

2011

The objective of this thesis was on the one hand to identify the motives for dropout handballers and the basketballers Syrian women and to test on the other hand three theoretical models which explain the dropout of sport. A first study (N = 402) attempted to identify the reasons for dropout for these players. The results showed that the players estimate that certain reasons (e.g., to get pregnant, to have a husband which does not make it possible to his wife any more to make sport) are very important to give up sport. Some reasons are in function of the type and level of players as well as the age and level of experience. A second study (N = 328) tested the model of dropout of Sarrazin and…