Article Abstract:
Many cell activities are influenced by external molecules. Many signaling events seem to involve diffusible factors in the early development of flies, nematodes, frogs and the chick. For a signal to function as a morphogen it must be shown that cells respond directly to extracellular signaling molecules and cells exhibit two different responses. Activin can switch animal cap cells of a blastula at picomolar concentrations from their normal fate to mesodermal cell types. It is believed that some cells can perceive their position in a concentration gradient, independently, by counting the receptors activated by a morphogen.
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Article Abstract:
A review was done to understand the structure and motor activity of kinesin. Kinesin is a binding protein that attaches and moves along a microtubule substrate which gives power to various physiological transport processes. The two independent globular heads of the protein were found to coordinate with each other such that binding and hydrolysis of adenosine triphosphate by one leads to adenosine diphosphate release of the other. This finding provides evidence that dimeric kinesin advances its heads alternately so that one stays bound to the substrate at any time.
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Article Abstract:
X-ray crystallography has been used to solve the dimeric form of kinesin motor and neck domain from rate brian with bound ADP. The two dimer heads are linked by a coiled-coil alpha-helical interaction and are broadly similar. The heads have rotational symmetry around an axis near to the coiled-coil. The arrangement is not compatible with the microtubule lattice.
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