Anglerfish proinsulin and insulin were selectively labeled with [(14)C]isoleucine, while proglucagon, conversion intermediate(s), and glucagon were selectively labeled with[(3)H]tryptophan. After various periods of continuous or pulse-chase incubation, islet tissue was subjected to subcellular fractionation. Fraction extracts were analyzed by gel filtration for their content of precursor, conve...

In the present study we investigated the subcellular localization of squalene synthase (farnesyl-diphosphate:farnesyl-diphosphate farnesyltransferase, EC 2.5.1.21). Squalene synthase catalyzes the formation of squalene from trans-farnesyl diphosphate in two distinct steps and is the first committed enzyme for the biosynthesis of cholesterol. Recently, a truncated form of the enzyme from rat hep...

The lipids of intact human platelets were labeled in vitro with acetate-1-(14)C, and the distribution of radioactivity in individual fatty acids and in lipid classes was examined in platelet subcellular fractions separated by sucrose density gradient ultracentrifugation. The distribution of newly formed fatty acids among individual lipid classes was similar in all subcellular components, and no...

Here we describe a fast and efficient subcellular fractionation procedure that permits lysosomes to be separated from endosomes. Differential centrifugation is used to isolate a subcellular fraction containing both endosomes and lysosomes. Because lysosomes are sensitive to osmotic stress, hypotonic conditions destroy them, whereas endosomes, which are osmotically insensitive, stay intact. We d...

A global protein survey is needed to gain systems-level insights into mammalian cell signaling and information flow. Human Jurkat T leukemic cells are one of the most important model systems for T cell signaling study, but no comprehensive proteomics survey has been carried out in this cell type. In the present study we combined subcellular fractionation, multiple protein enrichment methods, an...

Mobile lipids have been detected by proton nuclear magnetic resonance (NMR) in animal and human tumors (cultured cells, biopsies, and in vivo), but their origin and subcellular location are still unclear. They have been associated with malignancy, metastatic ability, drug resistance, and necrosis. We wanted to determine whether these lipids are located within plasma membrane microdomains or in ...