Comparison of the inferred amino acid sequence of outer-membrane protein PIB from gonococcal strain P9 with those from other serovars reveals that sequence variations occur in two discrete regions of the molecule centred on residues 1% (Varl) and 237 (Var2). A series of peptides spanning the amino acid sequence of the protein were synthesized on solid-phase supports and reacted with a panel of monoclonal antibodies (mAbs) which recognize either type-specific or conserved antigenic determinants on PIB. Four type-specific mAbs reacted with overlapping peptides in Varl between residues 192-198. Analysis of the effect of amino acid substitutions revealed that the mAb specificity is generated by differences in the effect of single amino acid changes on mAb binding, so that antigenic differences between strains are revealed by different patterns of reactivity within a panel of antibodies. The variable epitopes in Varl recognized by the type-specific mAbs lie in a hydrophilic region of the protein exposed on the gonococcal surface, and are accessible to complement-mediated bactericidal lysis. In contrast, the epitope recognized by mAb SM198 is highly conserved but is not exposed in the native protein and the antibody is non-bactericidal. However, the conserved epitope recognized by mAb SM24 is centred on residues 198-199, close to Varl, and is exposed for bactericidal killing.

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An Arabidopsis thaliana gene (UBC6) encoding a homologue to ubiquitin-conjugating enzymes has been isolated which is capable of encoding a protein of 183 amino acids of ca. 21 kDa. Northern analysis indicates that the gene is expressed in flowers, seeds and, to a somewhat lesser extent, in 10-day seedlings but not in mature leaves, callus and pre-flowering plants. This pattern of expression is confirmed using transgenic Arabidopsis plants containing a UBC6 promoter-GUS gene fusion construct. These plants display GUS activity in mature anthers prior to dehiscence, in developing embryos, sepals and the style after pollination.

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v 1.5 recordings from cardiomyocyte-cardiomyocyte and cardiomyocyte-fibroblasts junctions. Functional and dominant-negative Cx43 EGFP adenoviruses were used to probe active/inactive junctions. The Na v b1 adhesion inhibitor peptide (badp1) was tested. Whole-cell Na v -currents were recorded to separate non-junctional badp1 effects. To assess transdepolarisation, current-clamp and optical measurements were combined. Plasma membranes were analysed for junctional protein density. Exogenously-delivered Cx43 EGFP trafficked to regions where Na v activity and cluster size were increased relative to native Cx43-junctions (p=0.015). Smaller Na v -clusters (5-10) were abundant at native junctions, larger clusters (20-30) predominated at Cx43 EGFP -junctions. Acute badp1 peptide treatment caused Na v downregulation at native (p<0.01) and Cx43 EGFP -rich junctions (p<0.001). Lack of badp1 effect on the whole-cell current supports a role for b1 as a trans-cellular adhesion molecule. Blockade of cardiomyocyte transactivation using optical/electrical recordings was demonstrated with badp1 pre-treatment. Reduced Na v -current and smaller channel clusters were found at cardiomyocyte-fibroblast versus cardiomyocyte-cardiomyocytes junctions. Membranes from junction-remote regions showed similar currents, but different Na v -cluster size. Strength of intercellular junctions depend on Na v -current, intact Na v b1 and the amount of functional Cx43. Cardiac junction type hetero-vs. homo-cellular governs Na v activity and distribution. Novel badp1 peptide establishes importance of perinexal regions for signal propagation. Our findings and biophysical approach elucidate molecular origin of arrhythmogenic activity within/around GJ, revealing rationale for the anti-arrhythmic effects of Na v b1-mediated adhesion.