The purpose of this study was to assess (1) whether or not cardiopulmonary bypass surgery would decrease platelet secretory ADP, (2) whether or not patients with severe valvular disease have a decrease in platelet secretory ADP, and (3) whether or not such a decrease in secretory ADP is associated with surgical bleeding. Total and releasable platelet ADP and ATP were measured by the luciferase ...

There is accumulating evidence that proteins can be retained in the endoplasmic reticulum by a mechanism that is believed to monitor the oxidation status of one or more cysteines in their sequences. For example, a single cysteine residue critical for retention of secretory IgM assembly intermediates has been mapped to the C-terminal cysteine, Cys575, of the secretory mu chain. Little is known c...

Prostate apoptosis response-4 (Par-4) is a tumor-suppressor protein that induces apoptosis in cancer cells, but not in normal cells. The cancer-specific pro-apoptotic action of Par-4 is encoded in its centrally located SAC domain. In this study, to further enhance the anti-cancer effect of Par-4 in order to overcome the limitations of peptide therapy, a recombinant adeno-associated virus was co...

Newly synthesized hormones have been suggested to be preferentially secreted by various neuroendocrine cells. This observation indicates that there is a distinct population of secretory granules containing new and old hormones. Recent development of fluorescent timer proteins used in bovine adrenal chromaffin cells revealed that secretory vesicles segregate into distinct age-dependent populatio...

Optical control of protein interactions has emerged as a powerful experimental paradigm for manipulating and studying various cellular processes. Tools are now available for controlling a number of cellular functions, but some fundamental processes, such as protein secretion, have been difficult to engineer using current optical tools. Here we use UVR8, a plant photoreceptor protein that forms ...

Previous work has shown that phorbol esters or diacylglycerol trigger cortical granule exocytosis in Xenopus oocytes. We sought to identify the isoform(s) of protein kinase C (PKC) that mediate(s) this regulated secretory event. Because this process is initiated by lipid activators of PKC but is independent of calcium ions, we focused on the family of novel (calcium-independent) PKCs. Pharmacol...

Jaundiced babies undergoing phototherapy often develop diarrhoea. The cause of it is still uncertain. Increasing evidence supports a role of a secretory mechanism for the diarrhoea. We therefore studied the effects of bile from congenitally jaundiced rats undergoing phototherapy and of unconjugated bilirubin on rat small intestine in vivo and in vitro. Results suggest that: (1) the bile from ho...

Fusion of a vesicle with its target membrane is preceded by tethering or docking. However, the physical mechanism of vesicle-tethering is unknown. To study this mechanism, we used eosinophil secretory granules, which undergo stimulated homotypic fusion events inside the cell during degranulation. Using a dual optical trap system, we observed tether formation between isolated eosinophil secretor...