DdCAD-1 is a 24-kD Ca2+-dependent cell- cell adhesion molecule that is expressed soon after the initiation of development in Dictyostelium cells. DdCAD-1 is present on the cell surface as well as in the cytosol. However, the deduced amino acid sequence of DdCAD-1 lacks a hydrophobic signal peptide or any predicted transmembrane domain, suggesting that it may be presented on the cell surface via...

One proposed contributory mechanism for depressed ventricular performance after hypothermic, hyperkalemic cardioplegic arrest is a reduction in myocyte contractile function caused by alterations in intracellular calcium homeostasis. Because 2,3-butanedione monoxime decreases intracellular calcium transients, this study tested the hypothesis that 2,3-butanedione monoxime supplementation of the h...

INTRODUCTION AND OBJECTIVES To investigate negative contractile responses in the left ventricle during low-dose dobutamine (LDD) gated single-photon emission computed tomography (SPECT) in patients with ischemic cardiomyopathy. METHODS Sixty-eight consecutive patients (mean age, 60 + or - 11 years; 7 male) with ischemic cardiomyopathy (i.e., left ventricular ejection fraction [LVEF] < or = 40...

During cytokinesis, fission yeast and other fungi and bacteria grow a septum that divides the cell in two. In fission yeast closure of the circular septum hole by the β-glucan synthases (Bgs) and other glucan synthases in the plasma membrane is tightly coupled to constriction of an actomyosin contractile ring attached to the membrane. It is unknown how septum growth is coordinated over scales o...

The BEACH family of proteins is a novel group of proteins with diverse roles in eukaryotic cells. The identifying feature of these proteins is the BEACH domain named after the founding members of this family, the mouse beige and the human Chediak-Higashi syndrome proteins. Although all BEACH proteins share a similar structural organization, they appear to have very distinct cellular roles, rang...

In reviewing work on cytoplasmic contractile proteins and the contributions made to this field by The Journal of Cell Biology, some perspective is gained by first pointing out that most cell biologists were not aware of the existence of these important cellular constituents more than 12 years ago. Times have changed, and today cytoplasmic contractile protein research is one of the busiest areas...

Like animal cells, fission yeast divides by assembling actin filaments into a contractile ring. In addition to formin Cdc12p and profilin, the single tropomyosin isoform SpTm is required for contractile ring assembly. Cdc12p nucleates actin filaments and remains processively associated with the elongating barbed end while driving the addition of profilin-actin. SpTm is thought to stabilize matu...

Cell cycle ends with cytokinesis that is the physical separation of a cell into two daughter cells. For faithful cytokinesis, cells integrate multiple processes, such as actomyosin ring formation, contraction and plasma membrane closure, into coherent responses. Linear actin assembly by formins is essential for formation and maintenance of actomyosin ring. Although budding yeast's two formins, ...

Paxillins are a family of conserved LIM domain-containing proteins that play important roles in the function and integrity of the actin cytoskeleton. Although paxillins have been extensively characterized by cell biological and biochemical approaches, genetic studies are relatively scarce. Here, we identify and characterize a paxillin-related protein Pxl1p in the fission yeast Schizosaccharomyc...

We present a model for the actin contractile ring of adherent animal cells. The model suggests that the actin concentration within the ring, and consequently the power that the ring exerts both increase during contraction. We demonstrate the crucial role of actin polymerization and depolymerization throughout cytokinesis, and the dominance of viscous dissipation in the dynamics. The physical or...