Peter Sheterline

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The free calcium ion concentration, [Ca2+]i, in the cytoplasmic matrix of quin2-loaded neutrophil leucocytes increases rapidly after addition of concanavalin A. This increase is effectively abolished by a short (3 min) preincubation with 10 nM-TPA (12-O-tetradecanoylphorbol 13-acetate). TPA also inhibits a [Ca2+]i rise of similar magnitude induced by low(More)
Skeletal muscle actin labelled with pyrene was used to measure the critical concentration (Cc) for assembly in conditions designed to approximate the ionic environment in the cytoplasm. Under these conditions (0.1 M-KCl, 2 mM-MgCl2, 1.1 mM-ATP, 0.1 mM-CaCl2, 0.5 mM-ethyleneglycol-bis(beta-aminoethylether)N,N'-tetraacetic acid, 0.25 mM-2-mercaptoethanol, 20(More)
An experimental approach is described that enables the analysis of interactions between exogenous surface ligands and components of the cytoplasm in neutrophil leukocytes. Neutrophils treated with the nonionic detergent Lubrol PX, under controlled conditions, yield intact detergent-insoluble ghosts. Morphological analysis of neutrophil ghosts shows that(More)
Ductal infiltrating carcinoma (d.i.c.) of human breast is a highly invasive neoplasm characterized by enhanced deposition of collagen. Paradoxically, enhanced collagen deposition is not correlated with inhibition of the migration of tumour cells into the host tissue. d.i.c. is characterized by the reappearance of 'embryonic' type I-trimer collagen and an(More)
The phorbol ester 12-O-tetradecanoyl-phorbol-13-acetate (TPA), at nanomolar concentrations, induces rapid (t1/2 approximately 30 s) protrusion of multiple petal-shaped lamellae by neutrophil leucocytes. Lamellae are richly endowed with actin filaments as determined by the localization of rhodamine-phalloidin, suggesting extensive assembly at the cell(More)
The phagocytic pathway for the uptake of multivalent Fc complexes by neutrophil leukocytes can be partially dissected by using a pulse-chase protocol at different chase temperatures. Utilising a deoxyribonuclease I inhibition assay, we show that an early response to recognition of phagocytic substrate by neutrophils is a rapid (less than 10 sec)(More)
The effect of inorganic phosphate (Pi) on the depolymerization of F-actin has been measured. Pi inhibits disassembly of pyrene-labelled F-actin at steady-state induced either by dilution, or by shearing, suggesting that Pi decreases the off rate constant, k-, for dissociation. This effect of Pi is maximal at 20 mM, unlike the effect of Pi in reducing the(More)
Experiments were performed to determine the effects of interrupting the flux of actin monomers between unpolymerised and polymerised pools in PtK2 cells by (1) microinjecting exogenous polymerisation nuclei and (2) blocking endogenous assembly sites with low concentrations of cytochalasin D. Fluorescent actin oligomers were prepared by glutaraldehyde(More)