scholarly journals Partitioning, diffusion, and ligand binding of raft lipid analogs in model and cellular plasma membranes

2012 ◽  
Vol 1818 (7) ◽  
pp. 1777-1784 ◽  
Author(s):  
Erdinc Sezgin ◽  
Ilya Levental ◽  
Michal Grzybek ◽  
Günter Schwarzmann ◽  
Veronika Mueller ◽  
...  
Keyword(s):  
Ligand Binding ◽  
Plasma Membranes

Mouse sperm-egg plasma membrane interactions: analysis of roles of egg integrins and the mouse sperm homologue of PH-30 (fertilin) beta

1995 ◽  
Vol 108 (10) ◽  
pp. 3267-3278 ◽  
Author(s):  
J.P. Evans ◽  
R.M. Schultz ◽  
G.S. Kopf
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequence ◽  
Guinea Pig ◽  
Ligand Binding ◽  
Zona Pellucida ◽  
Plasma Membranes ◽  
Signal Sequence ◽  
Rgd Peptides ◽  
Mouse Sperm ◽  
Disintegrin Domain

The guinea pig sperm protein, PH-30 (also known as fertilin), is postulated to participate in the interaction between the sperm and egg plasma membranes. The beta subunit of guinea pig PH-30 (gpPH-30 beta) contains a domain with homology to disintegrins, snake venom proteins that bind to integrins via an integrin-binding domain containing the tripeptide RGD. This raises the question of whether an egg integrin serves as a receptor for PH-30. Although mouse eggs express integrin subunits, their role in mouse fertilization is unresolved. Therefore, we examined fertilization for two different hallmarks of integrin function, namely, dependence of ligand binding on divalent cations and the ability to inhibit ligand binding with RGD peptides. We demonstrate that sperm binding to zona pellucida-free eggs is supported by Ca2+, Mg2+, or Mn2+. Ca2+ was necessary and sufficient for sperm-egg fusion, with 2.5 mM Ca2+ being the most effective concentration. In addition, fertilization could be partially inhibited with various RGD peptides, which caused a decrease in sperm-egg fusion by 30–58%. This partial inhibition of fusion with RGD peptides prompted the cloning of the mouse homologue of gpPH-30 beta (hereafter referred to as mPH-30 beta) to determine if it possessed the tripeptide RGD or a different amino acid sequence in its disintegrin domain. mPH-30 beta, which is expressed during meiotic and post-meiotic phases of spermatogenesis, shares significant similarities to gpPH-30 beta throughout the length of the molecule, from the signal sequence to the cytoplasmic tail. The full-length deduced amino acid sequence of mPH-30 beta. The disintegrin domain of mPH-30 beta has the tripeptide QDE (instead of RGD) in its cell recognition region. Peptides containing this QDE sequence decrease the binding and fusion of sperm with zona pellucida-free eggs by approximately 70%, suggesting that the disintegrin domain of mPH-30 beta participates in the interaction between sperm and egg membranes.

Characterization of the receptor for glucagon-like peptide-1(7–36)amide on plasma membranes from rat insulinoma-derived cells by covalent cross-linking

1989 ◽  
Vol 2 (2) ◽  
pp. 93-98 ◽  
Author(s):  
R. Göke ◽  
T. Cole ◽  
J. M. Conlon
Keyword(s):  
Ligand Binding ◽  
Protein Complex ◽  
Plasma Membranes ◽  
Specific Binding ◽  
Binding Protein ◽  
Single Class ◽  
Intact Cells ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1 ◽  
Rat Insulinoma

ABSTRACT 125I-Labelled glucagon-like peptide-1(7–36)amide was cross-linked to a specific binding protein in plasma membranes prepared from RINm5F rat insulinoma-derived cells using disuccinimidyl suberate. Consistent with the presence of a single class of binding site on the surface of intact cells, only a single radiolabelled band at Mr 63 000 was identified by SDS-PAGE after solubilization of the ligand—binding protein complex. The band was not observed when 10 nm glucagon-like peptide-1(7–36)amide was included in the binding assay, but 1 μm concentrations of glucagon-like peptide1(1–36)amide, glucagon-like peptide-2 and glucagon did not decrease the intensity of labelling. No change in the mobility of the band was observed under reducing conditions, suggesting that the binding protein in the receptor is not attached to other subunits via disulphide bonds. In control incubations using plasma membranes from pig intestinal epithelial cells, which do not contain specific binding sites for glucagon-like peptide-1(7–36)amide, no cross-linked ligand-binding protein complex was observed.

scholarly journals Partitioning, Diffusion, and Ligand Binding of Raft Lipid Analogs in Model and Cellular Plasma Membranes

2012 ◽  
Vol 102 (3) ◽  
pp. 296a-297a
Author(s):  
Erdinc Sezgin ◽  
Ilya Levantal ◽  
Guenter Schwarzmann ◽  
Veronika Mueller ◽  
Alf Honigmann ◽  
...  
Keyword(s):  
Ligand Binding ◽  
Plasma Membranes

A simple and rapid assay for measuring radiolabeled ligand binding to purified plasma membranes

1983 ◽  
Vol 131 (2) ◽  
pp. 430-437 ◽  
Author(s):  
William M. Mackin ◽  
Chi-Kuang Huang ◽  
Barbara-Jean Bormann ◽  
Elmer L. Becker
Keyword(s):  
Ligand Binding ◽  
Plasma Membranes ◽  
Rapid Assay

Control of acetylcholine receptors in skeletal muscle

1979 ◽  
Vol 59 (1) ◽  
pp. 165-227 ◽  
Author(s):  
D. M. Fambrough
Keyword(s):  
Skeletal Muscle ◽  
Ligand Binding ◽  
Binding Site ◽  
Binding Sites ◽  
Acetylcholine Receptors ◽  
Plasma Membranes ◽  
Neuromuscular Junctions ◽  
Molecular Entity ◽  
Receptor Structure ◽  
Ach Receptors

An ACh receptor is the molecular entity that, in its native habitat, possesses the binding sites for ACh and all the other components required to generate the ion channels mediating the ACh response. Narrower definitions of an ACh receptor (as the binding site for ACh or the polypeptide chain that is folded to form the binding site) could lead to semantic arguments about receptor structure. Experimentally, ACh receptors are defined by their total function (when electrophysiological tests are used) or by ligand binding. There is no evidence that the ligand-binding portions of ACh receptors ever exist in vivo without the associated channel-forming mechanism and vice versa. Most data are consistent with the idea that detergent-solubilized glycoproteins retaining the ACh binding sites of the receptor also include the channel-forming components, although it appears that the mechanism is prone to denaturation or proteolytic damage. Studies of receptor-rich membranes and of solubilized receptor glycoprotein have not yet yielded a totally satisfactory image of receptor structure. Most evidence favors an ACh receptor composed of three or four different types of glycosylated polypeptide chains organized into a unit of aggregate molecular weight about 300,000--400,000 daltons. Plasma membranes are dynamic structures in two different ways. First, their constituent molecules are in rapid thermal motion and, when these molecules are not tethered to extramembranous structures or mired in large aggregates, they fairly rapidly change their position in the plane of the lipid bilayer. Second, all membrane components are continually being synthesized and degraded. Acetylcholine receptors participate in both aspects of this dynamism. In this review it is proposed that the number and the distribution of ACh receptors in skeletal muscle are controlled by modulation of receptor metabolism and modulation of associations between receptor molecules or between receptors and other, as yet unidentified, elements in neuromuscular junctions and at extrajunctional sites where receptors are clustered. The arrangements of receptors in skeletal muscle and the total number of receptors in skeletal muscle may be regulated by separate mechanisms. Clusters of ACh receptors apparently can form spontaneously in extrajunctional areas of denervated muscles and in tissue-cultured embryonic muscle. Such clusters may be positionally stable and the receptor molecules in them may be highly restricted in mobility. Nevertheless, these receptors have average lifetimes on the order of 20 h, just like the nonclustered, mobile extrajunctional receptors. Receptor clusters also form at sites of innervation. In the chick embryo the junctional receptor molecules remain short-lived. The metabolism of ACh receptors is highly regulated. The biosynthesis of receptors commences during myogenesis at about the time myogenic cells become competent to fuse. Later, biosynthesis is dramatically repressed by muscle activity and possibly by other factors...

On the structural organization of biological pumps and channels

1984 ◽  
Vol 42 ◽  
pp. 138-141
Author(s):  
G. Zampighi ◽  
M. Kreman
Keyword(s):  
Active Transport ◽  
Transport System ◽  
Plasma Membranes ◽  
Transport Proteins ◽  
Molecular Organization ◽  
Passive Transport ◽  
Concentration Gradients ◽  
Cell Functions ◽  
Natural Concentration ◽  
Active Transport System

The plasma membranes of most animal cells contain transport proteins which function to provide passageways for the transported species across essentially impermeable lipid bilayers. The channel is a passive transport system which allows the movement of ions and low molecular weight molecules along their concentration gradients. The pump is an active transport system and can translocate cations against their natural concentration gradients. The actions and interplay of these two kinds of transport proteins control crucial cell functions such as active transport, excitability and cell communication. In this paper, we will describe and compare several features of the molecular organization of pumps and channels. As an example of an active transport system, we will discuss the structure of the sodium and potassium ion-activated triphosphatase [(Na+ +K+)-ATPase] and as an example of a passive transport system, the communicating channel of gap junctions and lens junctions.

Membrane microdomains: lessons from microscopy

1995 ◽  
Vol 53 ◽  
pp. 776-777
Author(s):  
J.M. Robinson ◽  
J.M Oliver
Keyword(s):  
Spatial Distribution ◽  
Plasma Membrane ◽  
Epithelial Cells ◽  
Plasma Membranes ◽  
Cell Types ◽  
Imaging Modalities ◽  
Membrane Microdomains ◽  
Membrane Domains ◽  
Lateral Heterogeneity ◽  
Functional Importance

Specialized regions of plasma membranes displaying lateral heterogeneity are the focus of this Symposium. Specialized membrane domains are known for certain cell types such as differentiated epithelial cells where lateral heterogeneity in lipids and proteins exists between the apical and basolateral portions of the plasma membrane. Lateral heterogeneity and the presence of microdomains in membranes that are uniform in appearance have been more difficult to establish. Nonetheless a number of studies have provided evidence for membrane microdomains and indicated a functional importance for these structures.This symposium will focus on the use of various imaging modalities and related approaches to define membrane microdomains in a number of cell types. The importance of existing as well as emerging imaging technologies for use in the elucidation of membrane microdomains will be highlighted. The organization of membrane microdomains in terms of dimensions and spatial distribution is of considerable interest and will be addressed in this Symposium.

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