Hetero-dimer

Heterodimeric receptors, 182t Hetero dimerization, 181 Heterologous desensitization, 34 High-throughput screening agonists, 156 antagonists, 156... 

Pfeiffer, R., et al. Luminal hetero-dimeric amino acid transporter defective in cystinuria. Mol. Biol. Cell 1999, 10, 4135-4147. 

Breast Cancer Resistance Protein (BCRP, also known as MXR or ABCP), first cloned from mitoxantrone and anthracycline-resistant breast and colon cancer cells [188, 189] is a half-transporter efflux pump believed to function as a homo-or hetero-dimer. Following its identification, BCRP-mediated drug resistance was observed for topoisomerase inhibitors including camptothecins [190, 191] and in-dolocarbazoles [192]. In normal tissues, BCRP was detected in placental syncytio-trophoblasts, hepatocyte canalicular membrane, apical intestinal epithelia and vascular endothelial cells [193]. These findings support the important role BCRP plays in modulating topotecan bioavailability, fetal exposure and hepatic elimination [194]. Considering that the substrates and tissue distributions for BCRP overlap somewhat with MDR1 and MRPs [195], additional studies will be required to define the relative contribution of each of these transporters in the overall and tis-... 

Marushchak, D, Kalinin, S, Mikhalyov, I, Gretskaya, N. and Johansson, L. B. A. (2006). Pyrromethene dyes (BODIPY) can form ground state homo and hetero dimers Photophysics and spectral properties. Spectrochim. Acta Part A-Mol. Biomol. Spectrosc. 65, 113-122. 

Mercier, J. F., Salahpour, A., Angers, S., Breit, A., and Bouvier, M. (2002) Quantitative assessment of beta 1 and beta 2-adrenergic receptor homo and hetero-dimerization by bioluminescence resonance energy transfer. J. Biol. Chem. 277,44925 14931. 

A recent study has indicated that the skeletal rearrangement step in the B12-catalysed isomerization of methylmalonyl-CoA to succinyl-CoA occurs not by a radical pathway but by an anionic or organocobalt pathway. A computational study of the isomerization of allyl alcohol into homoallyl alcohol by lithium amide has pointed to a process proceeding via a transition state in which the proton is half transferred between carbon and nitrogen in a hetero-dimer. l,l-Dilithio-2,2-diphenylethene... 

Figure I. The hetero dimeric Core Binding Factor (CBF) transcription factor is comprised of one of three RUNX family proteins (a snbnnit) and a b-subimit, which is encoded by a single gene. The RUNX proteins contain two conserved and functional domains the runt homology domain (RHD) and the transcription activation domain (TAD). Interactions between the RHD and the hetero dimerization domain (HD) of CBFb are essential for most of the known activities of CBF. Synerigistic activity with a number of different transcription factors is well established.

Lenferink, A. E., R. Pinkas Kramarski, M. L. van de Poll, M. J. van Vugt, L. N. Klapper, E. Tzahar, H. Waterman, M. Sela, E. J. van Zoelen, and Y. Yarden. Differential endocytic routing of homo- and hetero-dimeric ErbB tyrosine kinases confers signaling superiority to receptor heterodimers. EMBO J. 17 3385-3397.1998. 

Effect of Ag+ complexation on relative aromaticity in various rings was examined by NICS in two representative cases. Structures and energies of the acetyl pyrene-Ag -pyrene hetero-dimer and acetyl pyrene-Ag -acetyl pyrene homo-dimer complexes were determined with the same model. Interestingly, only sandwich complexes were formed and no stable structures in which the silver ion was not sandwiched between two PAH units could be found. 

Cleavage of the Trt group of one chain 54 with a weak acid to give 55 and its subsequent thiolysis of the. S -SPy derivative of the second chain 57 directs the formation of the first interchain disulfide bond in 58. The second interchain disulfide bridge is formed between the two Acm-protected cysteine residues of the [bis(Acm), bis(tBu), mono-disulfide]-hetero-dimer 58 by treatment with iodine. Finally, treatment of 59 with chlorosilane/sulfoxide produces the third disulfide bond between the two tBu-protected cysteine residues yielding human insulin (42). 

Yu, L. Ishida, T. Ozawa, K. Akutsu, H. Horiike, K. Purification and characterization of homo- and hetero-dimeric acetate kinases from the sulfate-reducing bacterium Desulfovibrio vulgaris. J. Biochem., 129, 411-421 (2001)... 

Crystals of stoichiometric 1 1 mixtures of compounds that can complex with each other have been shown to form preferentially to pure crystals of the individual components. In some cases these crystals may have potential non-linear optical properties. An interesting example is the 1 1 mixture of p-aminobenzoic acid and 3,5-dinitrobenzoic acid. (15) A view of the crystal structure is shown in figure 3. Examination of this figure leads one to the hypothesis that the preference for the mixed crystal may be due to a) a more stable H-bonding interaction between the different benzoic acids in the hetero-dimer than in the homo-dimer b) the ability of the mixed crystal (hetero- dimers) to H-bond between their amino and nitro groups. It is likely that both of these factors play a role in the stability of the crystal structure. Calculational modelling can aid in determining the importance of these factors. 

The hetero-dimerization behavior of dye-modified -cyclodextrins with native CDs was investigated by means of absorption and induced circular dichroism spectroscopy in aqueous solution [43], Three types of azo dye-modified /i-CDs show different association behavior, depending on the positional difference and the electronic character of substituent connected to the CD unit in the dye moiety. p-Methyl Red-modified fi-CD (1), which has a 4-(dimethylamino)azobenzene moiety connected to the CD unit at the 4 position by an amido linkage, forms an intramolecular self-complex, inserting the dye moiety in its / -CD cavity (Figure 13). 1 also associates with native a-CD by inserting the dye residue into the a-CD cavity. The association constants for such hetero-dimerization are 198 M"1 at pH 1.00 and 305 M 1 at pH 6.59, which are larger than the association constants of 1 for / -CD (43 M 1 at pH 1.00). 

Kuwabara, T. Aoyagi, T. Takamura, M. Matsushita, A. Nakamura, A. and Ueno, A. (2002) Hetero-Dimerization of Dye-Modified Cyclodextrins with Native Cyclodextrins J. Org. Chem. 67, 720-725. 

Alcohols, ethers and certain amines also react and a broad series of compounds can be conveniently synthesized by the dimerization procedure. Typical examples are shown in Scheme 1, in which the new bond formed is marked in bold. For alcohols, ethers, and amines, highly selective attack at a C-H bond a to a heteroatom is observed. In cases where two different substances react, the two homo dimers and the hetero dimer are all formed. This can still be synthetically useful because the three compounds are often sufficiently different, either in polarity or volatility, to be readily separable by chromatography or fractional distillation. 

A remarkable feature of the Bcl-2 proteins is their ability to interact with one another to form either homo- or hetero-dimers (Oltvai et al., 1993). The formation of hetero-dimers between pro- and anti-apoptotic members suggests a competitive neutralization of their activities. A healthy cell maintains a balance between these groups of proteins and a destabilization in their relative concentration determines, at least in part, the decision for cell survival or cell death (Gross et al., 1999). 

Figure 5.19 Molecular shape of rotaxane 23 (n = 6), a hetero-dimeric assembly of a tetraloop tetra-urea 9 (stick representation) and tetra-tosylurea 4 (space filling), based on MD simulations. Ether groups (OY = OC5Hnn,) areomitted in the formula.

The monophthalocyanines 106 and 107 show a weak aggregation tendency in chloroform. The latter has a self-dimerization constant of 1,175 M-1. By contrast, the donor-acceptor bis(phthalocyanine) 99 exhibits a much stronger aggregation tendency with a dimerization constant of 1.1 x 106 M-1 in chloroform. It is believed that in addition to the hydrophobic effect, the two phthalocyanine halves of compound 99 may be considered as donor and acceptor subunits that interact with each other. As revealed by electron microscopy, 99 forms one-dimensional nanoaggregates through intermolecular interactions between its complementary donor and acceptor phthalocyanine units as shown in Fig. 8. The dimerization constant of 99 is about one order of magnitude lower than that observed for the hetero-dimerization of 106 and 107, which may be due to the cyclophane step that hinders the formation of columnar aggregates of double phthalocyanine dimer. 

Fig. 10.45. The structures of Gilman cuprates in halide- or cyanide-containing solution apart from the (homo-)dimer and/or the monomer in Figure 10.44, the (hetero-)dimers A or C and/or the corresponding "monomers with complex cation" B or D presented here can occur (but no "cyanocuprates" in which the bonding partner of the copper is a CN group).

The TLR4-MD2 hetero-dimer has complex ligand specificity. It can be activated by structurally diverse LPS molecules, and minor changes in synthetic derivatives of LPS can abolish their endotoxic potency (Raetz and Whitfield, 2002 Rietschel et al., 1994). The diversity in potency of LPS is derived from variance within lipid A, as observed in both the number and the length of fatty acid side chains and the presence of terminal phosphate residues with a variety of modifications. Optimal lipid A potency is achieved with bi-phosphorylated, hexa-acylated, lipid A species (Raetz and Whitfield, 2002). Lipid A moieties that deviate from this pattern often demonstrate a significant decrease in endotoxic activity (Alexander and Rietschel, 2001). 

Besides other homo and hetero dimers and trimers of 6, the trapping products 11 and 12 were obtained, with the conjugated diene 12 presumed to be a secondary product formed by thermal equilibration of the [2+2] cydoadduct 11 of 7 and 10. 

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