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Directional sensing by eukaryotic cells does not require polarization of chemoattractant receptors. The translocation of the PH domain-containing protein CRAC in D. discoideum to binding sites on the inner face of the plasma membrane reflects activation of the G protein-linked signaling system. Increments in chemoattractant elicit a uniform response around(More)
Two monoclonal antibodies, Y-3P and Y-8P, specific for conventional mouse Ia glycoprotein antigens are described. Both were raised by repeated immunization of primed mice with activated T cells over a period of 1 yr, and both detect a new and broad public Ia specificity. Both of the antibodies react with I-A subregion-controlled A alpha:A beta complexes of(More)
High-molecular-weight components (HMW) specifically associated with microtubule protein purified from porcine brain tissue were separated from tubulin by DEAE-Sephadex ion exchange chromatography. Analysis by viscometry, sedimentation, and electron microscopy of the unfractionated microtubule protein, separated HMW and tubulin fractions, and reconstituted(More)
CD4 T cell clones have been shown to be functionally heterogeneous in the mouse. However, it is not known if normal CD4 T cells are also functionally heterogeneous, or whether functional specialization is a result of cloning and long-term culture. To approach this question, a monoclonal antibody reacting with a subset of CD4 T cells has been prepared by(More)
Chicken erythrocyte beta tubulin, a tubulin variant with unique biochemical and assembly properties, is found to be specifically contained in two chicken blood cell types--erythrocytes and thrombocytes. The beta tubulin variant is absent or present in low amounts in a variety of white blood cell types and other body tissues, as determined by(More)
Dynamic interactions between the cytoskeleton and integrins control cell adhesion, but regulatory mechanisms remain largely undefined. Here, we tested the extent to which the autoinhibitory head-tail interaction (HTI) in vinculin regulates formation and lifetime of the talin-vinculin complex, a proposed mediator of integrin-cytoskeleton bonds. In an ectopic(More)
Microtubules can adjust their length by the mechanism of dynamic instability, that is by switching between phases of growth and shrinkage. Thus far this phenomenon has been studied with microtubules that contain several components, that is, a mixture of tubulin isoforms, with or without a mixture of microtubule-associated proteins (MAPs), which can act as(More)
We show that microtubule polymers can be immobilized selectively on lithographically patterned silane surfaces while retaining their native properties. Silane films were chemisorbed on polished silicon wafers or glass coverslips and patterned using a deep UV lithographic process developed at the Naval Research Laboratory. Hydrocarbon and fluorocarbon alkyl(More)
Two dimensional polyacrylamide gel electrophoresis of Non-Idet P-40 extracts and of specific Ia immunoprecipitates from [35S]methionine-labeled mouse spleen lymphocytes has revealed that the cell surface expression of some Ia antigens appears to be controlled by two genes. One locus, which maps in the I-A subregion, is probably the structural gene for an(More)