7-Dehydrobrefeldin A (7-oxo-BFA) is a brefeldin A (BFA) analog that, like BFA, is a potent phytotoxin of Alternaria carthami, a fungal pathogen of safflower (Carthamus tinctorius L.) plants. Both BFA and 7-oxo-BFA have been shown to be causal agents of the leaf spot disease of these plants. We have investigated the effects of 7-oxo-BFA on the secretion and the structure of the Golgi stacks of s...

The B subunit of verotoxin (VT1B) from enterohemorrhagic Escherichia coli is responsible for the attachment of the holotoxin to the cell surface, by binding to the glycolipid, globotriaosyl ceramide. After receptor-mediated endocytosis, the toxin is targeted to the Golgi complex by a process of retrograde transport. We took advantage of this unique property of VT1B to measure the pH of the Golg...

β-amyloid peptides (Aβ) are generated in intracellular compartments of neurons and secreted to form cytotoxic fibrils plaques. Dysfunctional membrane trafficking contributes aberrant Aβ production Alzheimer's disease. Endosomes represent one the major sites for recently Golgi has re-emerged also as a location amyloid precursor protein (APP) processing production. Based on recent findings, here ...

All-trans retinoic acid can specifically increase receptor mediated intoxication of ricin A chain immunotoxins more than 10,000 times, whereas fluid phase endocytosis of ricin A chain alone or ricin A chain immunotoxins was not influenced by retinoic acid. The immunotoxin activation by retinoic acid does not require RNA or protein synthesis and is not a consequence of increased receptor binding...

Comitin (p24) was first identified in Dictyostelium discoideum as a membrane-associated protein which binds in gel overlay assays to G and F actin. To analyze its actin-binding properties we used purified, bacterially expressed comitin and found that it binds to F actin in spin down experiments and increases the viscosity of F actin solutions even under high-salt conditions. Immunofluorescence ...

The conserved oligomeric Golgi (COG) complex is a heterooctameric complex that regulates intraGolgi trafficking and the integrity of the Golgi compartment in eukaryotic cells. Here, we describe a patient with a mild form of congenital disorder of glycosylation type II (CDG-II) that is caused by a deficiency in the Cog1 subunit of the complex. This patient has a defect in both N- and O-glycosyla...

Prothrombin is a vitamin K-dependent blood coagulation protein that undergoes posttranslational gamma-carboxylation and propeptide cleavage during biosynthesis. The propeptide contains the gamma-carboxylation recognition site that directs gamma-carboxylation. To identify the intracellular sites of carboxylation and propeptide cleavage, we monitored the synthesis of prothrombin in Chinese hamste...

Reticuloendothelial cells (RES cells) of human bone marrow were enzyme histochemically and cytochemically studied. Acid phosphatase staining (azo-dye method) was most suitable for the demonstration of RES cells. Attempts were made to classify RES cells of smear specimens into 5 types according to the size of nucleus, volume of cytoplasm and phagocytosis with the aid of acid phosphatase staining...

Molecular tools for fluorescent imaging of cells and their components are vital for understanding the function and activity of cells. Here, we report an imidazole functionalized pentameric oligothiophene, p-HTIm, that can be utilized for fluorescent imaging of cells. p-HTIm fluorescence in normal cells appeared in a peripheral punctate pattern partially co-localized with lysosomes, whereas a on...