33 research outputs found
Genomic location of the bovine growth hormone secretagogue receptor (Ghsr) gene and investigation of genetic polymorphism
The growth hormone secretagogue receptor (GHSR) is involved in the regulation of
energetic homeostasis and GH secretion. In this study, the bovine GHSR gene was mapped
to BTA1 between BL26 and BMS4004. Two different bovine GHSR CDS (GHSR1a and
GHSR1b) were sequenced. Six polymorphisms (five SNPs and one 3-bp indel) were also
identified, three of them leading to amino acid variations L24V, D194N, and Del R242.
These variations are located in the extracellular N-terminal end, the exoloop 2, and the
cytoloop 3 of the receptor, respectively
Variability and Action Mechanism of a Family of Anticomplement Proteins in Ixodes ricinus
Background: Ticks are blood feeding arachnids that characteristically take a long blood meal. They must therefore counteract host defence mechanisms such as hemostasis, inflammation and the immune response. This is achieved by expressing batteries of salivary proteins coded by multigene families. Methodology/Principal Findings: We report the in-depth analysis of a tick multigene family and describe five new anticomplement proteins in ixodes ricinus. Compared to previously described Ixodes anticomplement proteins, these segregated into a new phylogenetic group or subfamily. These proteins have a novel action mechanism as they specifically bind to properdin, leading to the inhibition of C3 convertase and the alternative complement pathway. An excess of non-synonymous over synonymous changes indicated that coding sequences had undergone diversifying selection. Diversification was not associated with structural, biochemical o, functional diversity, adaptation to host species or stage specificity but rather to differences in antigenicity. Conclusion/Significance: Anticomplement proteins from I. ricinus are the first inhibitors that specifically target a positive regulator of complement, properdin. They may provide new tools for the investigation of role of properdin in physiological and pathophysiological mechanisms. They may also be useful in disorders affecting the alternative complement pathway, Looking for and detecting the different selection pressures involved will help in understanding the evolution of multigene families and hematophagy in arthropods. © 2008 Couveur et al.Journal ArticleResearch Support, Non-U.S. Gov'tSCOPUS: ar.jinfo:eu-repo/semantics/publishe
A Fast Method To Predict Protein Interaction Sites From Sequences
A simple method for predicting residues involved in protein interaction sites is
proposed. In the absence of any structural report, the procedure identifies
linear stretches of sequences as "receptor-binding domains" (RBDs) by analysing
hydrophobicity distribution. The sequences of two databases of non-homologous
interaction sites eliciting various biological activities were tested; 59-80 %
were detected as RBDs. A statistical analysis of amino acid frequencies was
carried out in known interaction sites and in predicted RBDs. RBDs were predicted
from the 80,000 sequences of the Swissprot database. In both cases, arginine is
the most frequently occurring residue. The RBD procedure can also detect residues
involved in specific interaction sites such as the DNA-binding (95 % detected)
and Ca-binding domains (83 % detected). We report two recent analyses; from the
prediction of RBDs in sequences to the experimental demonstration of the
functional activities. The examples concern a retroviral Gag protein and a
penicillin-binding protein. We support that this method is a quick way to predict
protein interaction sites from sequences and is helpful for guiding experiments
such as site-specific mutageneses, two-hybrid systems or the synthesis of
inhibitors
The "Tilted Peptide Theory" links membrane insertion properties and fusogenicity of viral fusion peptides.
Class I fusion glycoproteins of viruses are involved in the fusion between viral envelope and cell membrane. A region located in the N-terminal domain of these glycoproteins, called the fusion peptide, is essential for fusion. Fusion peptides are able to induce by themselves in vitro membrane fusion. In this paper, we review the properties of those peptides related to their fusogenicity, in particular the correlation existing between their ability to insert obliquely in membranes and fusogenicity. This relation notably allows predicting successfully the minimal region of some fusion peptides sufficient to induce significant in vitro fusion. The notion of obliquity and fusogenicity is discussed in terms of the existing proposed mechanisms for viral fusion
The implication of fusion pepetides of class I viral fusion glycoproteins in the membrane fusion
peer reviewe
Prediction Of Membrane Protein Orientation In Lipid Bilayers: A Theoretical Approach
Over the past few years, several three-dimensional (3-D) structures of membrane
proteins have been described with increasing accuracy, but their relationship
with membranes are still not well understood. Recently, we have developed an
empirical method, Integral Membrane Protein and Lipid Association (IMPALA), to
predict the insertion of molecules (lipids, drugs) into lipid bilayers (Proteins
30 (1998) 357). The IMPALA uses a Monte Carlo minimisation procedure to calculate
the depth and the angle of insertion of membrane-interacting molecules taking
into account the restraints dictated by a lipid bilayer. In this paper, we use
IMPALA to test the insertion of 23 integral membranous proteins (IMPs) and 2
soluble proteins into membranes. Four IMP are studied in detail: OmpA,
maltoporin, MsCl channel and bacteriorhodopsin. The 3-D structures of the
proteins are kept constant and the insertion into membrane is monitored by
minimising the value of the restraint representing the sum of two terms, one for
lipid perturbation and the other for hydrophobicity. The two soluble proteins are
rejected from the membrane whereas, under the same conditions, all the membrane
proteins remain inside, if the solvent accessible surface of the amino acids
located inside the pore of porins is ignored. The results give the tilt angle of
the IMP helices or strands with respect to the membrane surface and the depth of
the protein mass centre insertion. We conclude that the restraint terms of IMPALA
could be used to study the insertion of model structures or complexes of proteins
within membranes