John E. Heuser

Learn More
Membrane traffic in eukaryotic cells involves transport of vesicles that bud from a donor compartment and fuse with an acceptor compartment. Common principles of budding and fusion have emerged, and many of the proteins involved in these events are now known. However, a detailed picture of an entire trafficking organelle is not yet available. Using synaptic(More)
Caveolae have been implicated in the transcytosis of macromolecules across endothelial cells and in the receptor-mediated uptake of 5-methyltetrahydrofolate. Structural studies indicate that caveolae are decorated on their cytoplasmic surface by a unique array of filaments or strands that form striated coatings. To understand how these nonclathrin-coated(More)
Chicken myosin-V is a member of a recently recognized class of myosins distinct from both the myosins-I and the myosins-II. We report here the purification, electron microscopic visualization, and motor properties of a protein of this class. Myosin-V molecules consist of two heads attached to an approximately 30 nm stalk that ends in a globular region of(More)
Amoebae of the eukaryotic microorganism Dictyostelium discoideum were found to contain an interconnected array of tubules and cisternae whose membranes were studded with 15-nm-diameter "pegs." Comparison of the ultrastructure and freeze-fracture behavior of these pegs with similar structures found in other cells and tissues indicated that they were the head(More)
Two seemingly unrelated experimental treatments inhibit receptor mediated endocytosis: (a) depletion of intracellular K+ (Larkin, J. M., M. S. Brown, J. L. Goldstein, and R. G. W. Anderson. 1983. Cell. 33:273-285); and (b) treatment with hypertonic media (Daukas, G., and S. H. Zigmond. 1985. J. Cell Biol. 101:1673-1679). Since the former inhibits the(More)
Using quick-freeze/deep-etch electron microscopy of recombinant proteins adsorbed to mica, we show that NSF, the oligomeric ATPase involved in membrane fusion, is a hollow 10 x 16 nm cylinder whose conformation depends upon nucleotide binding. Depleted of nucleotide, NSF converts to a "splayed" protease-sensitive conformation that reveals its subunit(More)
Lysosomes labeled by uptake of extracellular horseradish peroxidase display remarkable changes in shape and cellular distribution when cytoplasmic pH is experimentally altered. Normally, lysosomes in macrophages and fibroblasts cluster around the cell center. However, when the cytoplasmic pH is lowered to approximately pH 6.5 by applying acetate or by(More)
We describe the design and operation of a machine that freezes biological tissues by contact with a cold metal block, which incorporates a timing circuit that stimulates frog neuromuscular junctions in the last few milliseconds before thay are frozen. We show freeze-fracture replicas of nerve terminals frozen during transmitter discharge, which display(More)
The dynactin complex visualized by deepetch electron microscopy appears as a short filament 37-nm in length, which resembles F-actin, plus a thinner, laterally oriented filament that terminates in two globular heads. The locations of several of the constituent polypeptides were identified on this structure by applying antibodies to decorate the dynactin(More)
The success of Mycobacterium species as pathogens depends on their ability to maintain an infection inside the phagocytic vacuole of the macrophage. Although the bacteria are reported to modulate maturation of their intracellular vacuoles, the nature of such modifications is unknown. In this study, vacuoles formed around Mycobacterium avium failed to(More)