Cell membranes interaction

Several nonconventional cadherins that contain cadherin repeats have been described but they have specific features not found in the classical cadherins [1]. The cadherin Flamingo, originally detected in Drosophila, contains seven transmembrane segments and in this respect resembles G protein-coupled receptors. The extracellular domain of Flamingo and its mammalian homologs is composed of cadherin repeats as well as EGF-like and laminin motifs. The seven transmembrane span cadherins have a role in homotypic cell interactions and in the establishment of cell polarity. The FAT-related cadherins are characterized by a large number of cadherin repeats (34 in FAT and 27 in dachsous). Their cytoplasmic domains can bind to catenins. T- (=truncated-)cadherin differs from other cadherins in that it has no transmembrane domain but is attached to the cell membrane via a glycosylpho-sphatidylinositol anchor. 

Receptors may be integral components of mem-btanes (patticulatly the plasma membrane). The interaction of a hgand with its receptor may not involve the movement of either into the cell, but the intetaction tesults in the generation of a signal that influences inttaceUulat processes (transmembrane signahng). 

Are components of plasma membranes, where they may act as receptors and participate in cell adhesion and cell-cell interactions (eg, HS)... 

Further progress may derive from a more accurate definition of the chemical and physical properties of the humic substances present at the rhizosphere and how they interact with the root-cell apoplast and the plasma membrane. An interaction with the plasma membrane H -ATPase has already been observed however this master enzyme may not be the sole molecular target of humic compounds. Both lipids and proteins (e.g., carriers) could be involved in the regulation of ion uptake. It therefore seems necessary to investigate the action of humic compounds with molecular approaches in order to understand the regulatory aspects of the process and therefore estimate the importance of these molecules as modulators of the root-soil interaction. 

From the atomic to the macroscopic level chirality is a characteristic feature of biological systems and plays an important role in the interplay of structure and function. Originating from small chiral precursors complex macromolecules such as proteins or DNA have developed during evolution. On a supramolecular level chirality is expressed in molecular organization, e.g. in the secondary and tertiary structure of proteins, in membranes, cells or tissues. On a macroscopic level, it appears in the chirality of our hands or in the asymmetric arrangement of our organs, or in the helicity of snail shells. Nature usually displays a preference for one sense of chirality over the other. This leads to specific interactions called chiral recognition. 

Maurel, D., Kniazeff, J., Mathis, G., Trinquet, E., Pin, J. P. and Ansanay, FI. (2004). Cell surface detection of membrane protein interaction with homogeneous time-resolved fluorescence resonance energy transfer technology. Anal. Biochem. 329, 253-62. 

Zelazny, E., Borst, J. W., Muylaert, M., Batoko, H., Hemminga, M. A. and Chaumont, F. (2007). FRET imaging in living maize cells reveals that plasma membrane aquaporins interact to regulate their subcellular localization. Proc. Natl. Acad. Sci. USA 104, 12359-64. 

The principal difference in the overall protein composition of PNS and CNS myelin is that P0 replaces PLP as the major protein, although myelin-forming Schwann cells do express very low levels of PLP. It is interesting to note that PLP and P0 proteins, which are so different in sequence, post-translational modifications and membrane topology, may have similar roles in the formation of structures as closely related as myelin of the CNS and PNS respectively. Expression of P0 in transfected cells results in cell-cell interactions that are due to homophilic binding... 

Zieske JD, Mason VS, Wasson ME, Meunier SF, Nolte CJ, Fukai N, Olsen BR, Par-enteau NL. Basement membrane assembly and differentiation of cultured corneal cells Importance of culture environment and endothelial cell interaction. Exp Cell Res 214 621-633 (1994). 

During the last ten years, it has become apparent that calcium-dependent papain-like peptidases called calpains (EC 3.4.22.17) represent an important intracellular nonlysosomal enzyme system [35][36], These enzymes show limited proteolytic activity at neutral pH and are present in virtually every eukaryotic cell type. They have been found to function in specific proteolytic events that alter intracellular metabolism and structure, rather than in general turnover of intracellular proteins. Calpains are composed of two nonidentical subunits, each of which contains functional calcium-binding sites. Two types of calpains, i.e., /i-calpain and m-calpain (formerly calpain I and calpain II, respectively), have been identified that differ in their Ca2+ requirement for activation. The activity of calpains is regulated by intracellular Ca2+ levels. At elevated cytoplasmic calcium concentrations, the precursor procal-pain associates with the inner surface of the cell membrane. This interaction seems to trigger autoproteolysis of procalpain, and active calpain is released into the cytoplasm [37]. 

HIV-1 binds to the cell membrane through interaction of the viral envelope glycoprotein (gp) 120 with CD4 molecules on the cell smface. HIV-1 then fuses wifh fhe cell membrane as a result of interaction of gp 120 with chemokine receptors (CCR5 or CXCR4) on the cell. CCR5... 

In principle, liposomes can enter (target) cells through different pathways by direct fusion of liposomes and the plasma membrane (1) or by an endo-cytic uptake mechanism. Other liposome-cell interactions that have been described in the literature are absorption, phospholipid and protein exchange, and cell-induced leakage of liposome contents (2,3). 

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