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Protein phosphorylation has been suggested as an important control mechanism for the events leading toward the initiation and completion of mitosis. Using a monoclonal antibody recognizing a class of phosphoproteins abundant in mitotic cells, we demonstrated the localization of a subset of these phosphoproteins to several discrete mitotic structures. Patchy(More)
Immunocytochemistry provides important information on the localization of antigens in cells and tissues. However, the procedures used to prepare cells and tissues for immunocytochemical labeling may have deleterious effects on the results achieved. That is, the antigen of interest may be difficult or impossible to detect following labeling. These sorts of(More)
The MPM-2 monoclonal antibody recognizes a distinctive group of proteins that are associated with structural components of the mitotic apparatus. These proteins become phosphorylated and MPM-2 reactive during M-phase and appear to be required for both the onset and completion of M-phase. Based upon the analysis of reported MPM-2 reactive sequences, we have(More)
The effects of the protein phosphatase inhibitor okadaic acid were examined using the pig kidney cell line LLC-PK. At relatively low concentrations of the inhibitor (8-40 nM), cells became blocked in a metaphase-like mitotic state beginning 6-8 h after initial treatment. Spindle microtubules were present throughout the period of the mitotic block, but were(More)
The phosphoprotein composition of isolated CHO spindles was analyzed using the MPM-1 and MPM-2 antibodies, which are reactive with a phosphorylated epitope enriched in mitotic cells and present on the centrosome, kinetochores, midbody and fibers of the mitotic spindle. Several high molecular weight phosphorylated spindle proteins were detected on(More)
The cyclical phosphorylation and dephosphorylation of the centrosome during mitosis was analyzed by immunofluorescence methods using the MPM-2 antibody, which reacts with a subset of mitotic phosphoproteins. Quantification of MPM-reactivity indicated that centrosomal phosphorylation attained a maximal level just prior to anaphase onset. This level was(More)
In this article, we review the immunocytochemical literature with respect to a comparison between conventional colloidal gold and ultrasmall gold particles as immunoprobes. We discuss the relative advantages and disadvantages of each of these types of particles for immunocytochemical applications. We present results from our own laboratories, in which we(More)
The microtubule nucleation capacity of the centrosome increases dramatically as cells progress from interphase into mitosis. The increase in nucleation capacity of the centrosome correlates with the cell cycle-dependent localization of the mitotic protein monoclonal-2 (MPM-2) phosphoepitope-specific antibody to the mitotic centrosome. Therefore, the(More)
The human placenta is a complex organ whose proper function is crucial for the development of the fetus. The placenta contains within its structure elements of the maternal and fetal circulatory systems. The interface with maternal blood is the lining of the placenta, that is a unique compartment known as the syncytiotrophoblast. This large syncytial(More)
The microtubule cytoskeleton of human leukocytes has been difficult to study, in part, due to the lack of a reliable protocol for the indirect immunofluorescence staining of microtubules in these cells. We report here the development of a simple and reliable immunocytochemical labeling protocol for the examination of microtubules in leukocytes including(More)