Plakins

In addition to these extensive studies on electrophile-mediated intramolecular peroxydation of electron-rich C=C bonds, some examples of intramolecular hydroperoxide addition to electron-poor C=C bonds have been described. For example, several racemic analogues 371 of the naturally occurring plakinic acid were readily obtained by peroxymercuration followed by hydridodemercuration of the dienic acids 370 (Scheme 95 f °. Intramolecular Michael addition of hydroperoxide function to the double... 

Fujiwara, S., Takeo, N., Otani, Y., Parry, D. A. D., Kunimatsu, M., Lu, R., Sasaki, M., Matsuo, N., Khaleduzzaman, M., and Yoshioka, H. (2001). Epiplakin, a novel member of the plakin family originally identified as a 450-kDa human epidermal autoantigen Structure and tissue localization. / Biol. Chem. 276, 13340-13347. 

Aetin binding domain Plakin domain Spectrin repeals xmxa Coiled coil rod domain Plakin repeals... 

Fig. 2. Domain structure of plakin family members are shown on the right, along with a legend for each of the component domains. A single generic plectin isoform is shown here. Refer to text for a discussion of other plectin isoforms that primarily affect the N-terminus upstream of the ABD.

Fig. 3. A comparison of cell-cell and cell-substrated anchoring junctions. (A) Desmosomes anchor keratin filaments through desmoplakin. One half of a desmosome, which is an intercellular junction that anchors intermediate filaments (IFs) to the plasma membrane, is shown. The transmembrane desmosomal cadherins, desmogleins (Dsg) and desmocollins (Dsc), mediate adhesion through their extracellular domains, and associate with plakophilins (Pkp) and plakoglobin (Pg) through their cytoplasmic domains. These proteins in turn interact with the N-terminus of the plakin family member desmoplakin, which anchors IF to the junction through its G-terminus. (B) Endothelial VE-cadherin-based junctions anchor vimentin through...

Plakins are not the only proteins that tether IFs to the cell surface. A number of other proteins localized to cell surface structures including desmosomes, focal contacts, and muscle costameres also contribute to IF anchorage at plasma membranes. IFs may also associate with cell surface receptors outside of ultrastructurally distinct structures, a topic that will be dealt with below. 

Bornslaeger, E. B., Corcoran, C. M., Stappenbeck, T. S., and Green, K. J. (1996). Breaking the connection Displacement of the desmosomal plaque protein desmo-plakin from cell-cell interfaces disrupts anchorage of intermediate filament bundles and alters intercellular junction assembly./. Biol. Chem. 134, 985-1002. 

Leung, C. L., Green, K. J., and Liem, R. K. (2002). Plakins A family of versatile cytolinker proteins. Trends Cell Biol. 12, 37-45. 

Mahoney, M. G., Aho, S., Uitto, J., and Stanley, J. R. (1998). The members of the plakin family of proteins recognized by paraneoplastic pemphigus antibodies include periplakin./ Invest. Derm. Ill, 308-313. 

Roper, K., and Brown, N. H. (2003). Maintaining epithelial integrity A function for gigantic spectraplakin isoforms in adherens junctions. / Cell Biol. 162, 1305-1315. Roper, K., Gregory, S. L., and Brown, N. H. (2002). The spectraplakins Cytoskeletal giants with characteristics of both spectrin and plakin families. /. Cell Sci. 115, 4215-4225. 

Ruhrberg, C., and Watt, F. M. (1997). The plakin family Versatile organisers of cytoskeletal architecture. Cun. Opin. Genet. Deuel. 7, 392-397. 

Triethysilyl-protected peroxycarbenium ions (42), generated from acetals (41) on treatment with SnCL, have been developed as the optimal reagents to effect addition to alkenes, which gives rise to a variety of 1,2-dioxolanes (43) in 28-92% yields. This novel method allowed the synthesis of plakinic acid analogues in three steps from the corresponding ketone and alkene.53... 

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