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Like neutrophilic leukocytes, differentiated HL-60 cells respond to chemoattractant by adopting a polarized morphology, with F-actin in a protruding pseudopod at the leading edge and contractile actin-myosin complexes at the back and sides. Experiments with pharmacological inhibitors, toxins, and mutant proteins show that this polarity depends on divergent,(More)
A key mediator of eukaryotic chemotaxis is the asymmetric accumulation of phosphatidylinositol-3,4,5-triphosphate (PIP3) on the cell membrane. Recent work has focused on understanding how a shallow external gradient of chemoattractant leads to an amplified internal gradient of PIP3. In this paper we dissect what fraction of this amplification is derived(More)
Transmembrane receptors for hormones, neurotransmitters, light, and odorants mediate their cellular effects by activating heterotrimeric guanine nucleotide– binding proteins (G proteins). Crystal structures have revealed contact surfaces between G protein subunits, but not the surfaces or molecular mechanism through which G␣␤␥ responds to activation by(More)
We previously characterized LePRK1 and LePRK2, pollen-specific receptor kinases from tomato (Muschietti et al., 1998). Here we identify a similar receptor kinase from maize, ZmPRK1, that is also specifically expressed late in pollen development, and a third pollen receptor kinase from tomato, LePRK3. LePRK3 is less similar to LePRK1 and LePRK2 than either(More)
The elimination of autoreactive T cells occurs via thymocyte apoptosis and removal by thymic phagocytes, but the sequence of events in vivo, and the relationship between thymocyte death and phagocytic clearance, are unknown. Here we address these questions by following a synchronized cohort of thymocytes undergoing negative selection within a(More)
While a plethora of in vivo models exist for studying infectious disease and its resolution, few enable factors involved in the maintenance of health to be studied in situ. This is due in part to a paucity of tools for studying subtleties of bacterial-host interactions at a cellular level within live organs or tissues, requiring investigators to rely on(More)
Developing thymocytes are screened for self-reactivity before they exit the thymus, but how thymocytes scan the medulla for self antigens is unclear. Using two-photon microscopy, we observed that medullary thymocytes migrated rapidly and made frequent, transient contacts with dendritic cells. In the presence of a negative selecting ligand, thymocytes(More)
The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. Abstract Developing thymocytes are screened for self-reactivity before exiting the thymus, but how thymocytes scan the medulla for self-antigens is unclear. Using two-photon microscopy, we observed that medullary thymocytes migrated rapidly(More)
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