Compartmentalized cAMP signalling is important in the regulation of Ca(2+) cycling in the heart

Co-ordinated myocyte handling of calcium is essential for efficient excitation-contraction coupling in the heart. The calcium cycling activity can be modulated by adrenergic stimulation and subsequent phosphorylation. Important functional consequences of phosphorylation include a greater influx of calcium through the voltage-dependent L-type Ca(2+) channel and a greater release of calcium from SR (sarcoplasmic reticulum) through the ryanodine R2 receptor. Furthermore, a more efficient reuptake through SERCA2 (sarcoplasmic/endoplasmic-reticulum Ca(2+)-ATPase 2) is a result of phosphorylation of its regulatory protein phospholamban. Compartmentalized signalling is important in this signalling cascade, and A-kinase-anchoring proteins play a central role by providing a high level of specificity.

Mapping of neutralization epitopes on infectious pancreatic necrosis viruses

We have characterized and mapped variable and conserved neutralization epitopes of serogroup A strains of aquatic birnaviruses. Epitope mapping using monoclonal antibodies (MAbs) and Escherichia coli-expressed deletion fragments of VP2 of the N1 strain of infectious pancreatic necrosis virus (IPNV) demonstrated that two variable epitopes, H8 and B9, depend on the variable region between amino acid 204-330. A conserved neutralization epitope, F2, was shown to depend on the same region as epitopes H8 and B9 but was additionally dependent on amino acids between 153-203. The neutralization epitopes H8, B9 and F2 were also shown to overlap by a competitive binding assay. One conserved neutralization epitope, AS-1, was not exposed on any of the recombinant VP2 deletion fragments and was therefore not possible to map. However, the MAbs AS1 and F2 were partly competitive indicating that these epitopes are overlapping. All neutralization epitopes were independent of a conserved non-neutralization epitope, E4. Our results demonstrate that the central third of VP2 contains several partly overlapping neutralization epitopes, both variable and conserved among serogroup A strains of IPNV.