Intracellular movement

Microtubules, an integral component of the cellular cy-toskeleton, consist of cytoplasmic tubes 25 nm in diameter and often of extreme length. Microtubules are necessary for the formation and function of the mitotic spindle and thus are present in all eukaryotic cells. They are also involved in the intracellular movement of endocytic and exocytic vesicles and form the major structural components of cilia and flagella. Microtubules are a major component of axons and dendrites, in which they maintain structure and participate in the axoplasmic flow of material along these neuronal processes. 

Amlodipine is a calcium-channel blocker that blocks the intracellular movement of calcium ions and hence slows the contractility of the myocardium and relaxes the vascular smooth muscle. The negative inotropic effects are rarely seen at therapeutic doses since amlodipine has a greater selectivity for vascular smooth muscle than for the myocardium. 

This system allows one ActA molecule to concentrate up to 96 profilin molecules, and. Listeria may concentrate as much as 0.5-1 mM profilin on its surface. Profilin markedly potentiates growth of actin filaments, and highly concentrated profilin in the polymerization zone would be expected to result in explosive actin filament assembly, thus generating the forces required for Listeria intracellular movement. 

The bipyridines increase myocardial contractility by increasing inward calcium flux in the heart during the action potential they may also alter the intracellular movements of calcium by influencing the sarcoplasmic reticulum. They also have an important vasodilating effect. Inhibition of phosphodiesterase results in an increase in cAMP and the increase in contractility and vasodilation. 

Intracellular movement None Cytoplasmic streaming, endocytosis, phagocytosis, mitosis, vesicle transport... 

Intracellular movements of insulin and its precursors. RER = rough endoplasmic reticulum. 

The reality is that there are numerous glucose sensors in the body, and that they are interconnected both by hormones and by the nervous system. Similarly, the fate of the glucose is complex, and control of the intracellular movements may be even more important than control of the uptake. 

The physiology of the intracellular movement of yeast /3-D-fruc-tofuranosidase in its formation has been the subject of various studies. Clearly, the enzyme is synthesized somewhere inside the... 

Calcitriol behaves like a steroid hormone. It is transported to the nucleus of renal distal tubule cells, intestinal epithelial cells, osteoclasts, and osteoblasts where it induces calbindins, vitamin D-dependent calcium binding proteins. Calbindins mediate the intracellular movement of calcium, from diet to blood, from blood to osteoid matrix, or from bone to blood. There are two calbindin proteins, each encoded by separate genes, one of molecular weight about 9 kDa (calbindin-D. ) and one of molecular weight 28 kDa (calbindin-D28K). Each binds micromolar amounts of calcium and each disappears from animals that are... 

Circulating catecholamines such as epinephrine also result in an intracellular movement of potassium by two mechanisms. They stimulate the /S-receptor, which directly activates the Na" " -K" " -ATPase pump. Secondly, they stimulate glycogenolysis, which raises blood glucose levels, thereby increasing insulin secretion. This dual mechanism is often used therapeutically in patients with hyperkalemia to normalize serum potassium concentrations. 

Unesterified fatty acids within cells are commonly bound by fatty acid-binding proteins (FABPs), which belong to a group of small cytosolic proteins that facilitate the Intracellular movement of many lipids. These proteins contain a hydrophobic pocket lined by p sheets (Figure 18-3). A long-chain fatty acid can fit into this pocket and Interact noncovalently with the surrounding protein. 

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