Trans interactions

The classical cadherins are translated as precursor because they are N-terminally cleaved to reveal the mature proteins. This processing is required to activate the cell adhesion function of cadherins. Cadherins interact in trans (i.e., from opposite cells) via the most N-terminal cadherin rqDeats. A short amino acid sequence within this repeat, histidine-alanine-valine (HAV), has been implicated in mediating cell-cell contacts as HAV peptides can disrupt cadherin-dependent cell adhesion. Besides the trans-interactions of cadherins, the extracellular domains are also capable of forming cis-dimers through lateral amino acid contacts between cadherin molecules on one cell. This dimerization again mainly involves the first cadherin repeat. A zipper model based on the pattern of alternating cis- and trans-dimers [1] for the adhesive interactions has been proposed. 

In general, in square-planar and octahedral complexes 1JML depends on the trans-ligand stronger donors reduce the 1JML-value [10]. Similarly, ] i pM.iv.-val-ues are usually greater for trans-interactions than for cis-interactions [10], which is clearly an important tool for structural characterization (see Fig. 11.4). 

The interpretation of interaction parameters is far from stredghtforward. Calculations on model systems (2 c), and comparisons between parameters and force constants in real systems (4), show that the parameters contain several different terms. Thus in octahedral carbonyls, the cis interaction parameter, which is smaller than the trans parameter, originates mainly from the true cis interaction force constant. The trans interaction parameter, on the other hand, contains only a small direct contribution, while the main terms are indirect and involve MC,MC and MC.C O interaction constants. Calculations on substituted... 

For the second and third transition series, the values J(L -M-L ) depend strongly on geometry, as indicated in 74 and 75, with the trans-interactions being normally much larger than those for the corresponding cis-compounds. 

A specific example can be found in the Rh-chemistry mentioned in connection with Figure 1.4. The complex RhPh(PPh3)(Binap), 11, shows very different J( P. P) values with the trans-interaction much larger than the cis. Taken together, the three different P chemical shifts and the various j( Rh, P) and J( P, P) values are all important indicators of the correct structure for this complex. 

An increment system has been derived for methyldecalins [230] and methylated perhy-drophenanthrenes [231] by regressional analysis, because these compounds are steroid models and the increments, in fact, have proved to be of help in carbon-13 shift assignments of steroids (Section 5.2). Eq. (4.2) permits prediction of <5C using the increments A, of structural elements in position l to the carbon atom k to be considered (Table 4.9). These increments clearly indicate the configurational influence of the y substituent, decreasing for example from eclipsed via gauche to trans interactions (I , > Vq > Vt and... 

Jorgensen, R. (1990). Altered gene expression in plants due to trans interactions between homologous genes. Trends in Biotechnology 8, 340-4. 

Boggs JM, Menikh A, Rangaraj G. Trans interactions between galactosylceramide and cerebroside sulfate across apposed bilayers. Biophys. J. 2000 78 874-885. 

The four individual domains are paired in two types of close trans-interaction (Fig. 4) [103,17], The VH and VL domains are paired by extensive contact between the... 

The formation of many cell-cell adhesions entails two types of molecular Interactions (Figure 6-3). First, CAMs on one cell associate laterally through their extracellular domains or cytosolic domains or both into homodimers or higher-order oligomers in the plane of the cell s plasma membrane these interactions are called intracellular, lateral, or els interactions. Second, CAM oligomers on one cell bind to the same or different CAMs on an adjacent cell these interactions are called Intercellular or trans interactions. Trans interactions sometimes Induce additional els Interactions and, as a consequence, yet even more trans interactions. 

CAMs. Subsequent trans interactions between distal domains of CAMs on adjacent cells generate a zipperlike strong adhesion between the cells. [Adapted from M. S. Steinberg and P M. McNutt, 1999, Curr. Opin. Cell Biot 11 554.]... 

Ishii J, Adachi H, Aoki J et al. SREC-II, a new member of the scavenger receptor type F family, trans-interacts with SREC-I through its extracellular domain. The Journal of Biological Chemistry 2002 277 39, 696-39, 702. 

Cotton s force field approximation for octahedral metal carbonyls (ie i trans cis been re-evaluated. A modified equation linking the cis and trans interaction constants in M(CO)g j (L) complexes (viz. k(p g=1.22kp/g+21.3) is suggested as a replacement. Also,... 

The transition state is precisely analogous to that in a ti cycloaddition, the only difference being that the reactants in the n cycloaddition are both even, while here R and S are both odd. We can therefore see at once that if the 71 systems in (176) both interact in cis fashion or both in trans fashion, the transition state will be of Huckel type, while a cis-trans interaction will lead to an anti-Hiickel transition state. 

ODN act as a decoy for specific transcription factors, and is used to attenuate the authentic cis-trans interaction, leading to removal of fra/is-factors from the endogenous c/s-elements and subsequent modulation of gene expression. We developed an ODN that targets nuclear factor kappa B (NF-kB), which plays a pivotal role in the coordinated activation of inflammatory cytokines and expression of adhesion proteins and chimera decoys for both NF-kB and Ets, and for both NF-kB and E2F. 

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