Export mechanism

Velichkova M, Hasson T. 2005. Keapl regulates the oxidation-sensitive shuttling of Nrf2 into and out of the nucleus via a Crml -dependent nuclear export mechanism. Mol Cell Biol 25 4501 1513. 

Despite large amounts of evidence concerning the requirements of protein secretion, the molecular mechanism of the process is still unclear. Various models of the export mechanism have been proposed. No one hypothesis accounts for all of the data collected to date it may be that one mechanism is insufficient to explain the many types of export that occur. In this section, some current models of protein secretion are... 

Fig. 4 The lipid influx/efflux rheostat model maintains lipid uptake and export mechanisms in a balance. ATP synthase is regulated by apoA-I or apoE leading to enhanced conversion of ATP to ADP. The absence of apoA-I would lead to enhanced sinking in phagocytosis since actin can bind ATP, polymerize, and form F-actin which is essential for type 11 phagocytosis. Hence apoA-I could lead to increased influx. On the other hand, apoA-I binds to ABCAl leading to enhanced lipid efflux. Dysfunction of this equilibrium may lead to severe disturbances of cellular lipid traffic. This is obvious in Tangier disease patients where ABCAl is inoperative and apoA-/-dependent cholesterol is absent. Cholesterol influx, however, is enhanced due to apoA-Z-dependent stimulation of ATP synthase B leading to cholesteryl ester formation and enhanced foam cell formation...

An efficient biological pump means that a large fraction of the system s net production is removed from the surface waters via export mechanisms. Factors that affect the efficiency of the biological pump are numerous and include nutrient supply and plankton community structure. 

A cell can ill-afford high internal concentrations of free ionic cadmium (or any other reactive metal that would bind indiscriminately to proteins). The internal concentration of Cd " " in most cells is thus tightly controlled by a variety of binding and/or export mechanisms. 

To mention some, in 1972, negotiations to supply mechanization facilities for zinc smelting and refining to foreign smelters started and contracts were signed successively. This opened the door for MESCO to export mechanization facilities, and thereafter, it has been successful in overseas marketing. Further, MESCO has established a relationship with Outokumpu of Finland for copper smelter facilities. In Japan, MESCO has delivered facilities not only to MMS but also to other companies which are in the same trade. 

The final steps leading to the synthesis of chloroplast (CP) lipids take place in the envelope membranes. Over 90% of the CP lipids belong to thylakoid membranes (TM) [1]. Since TM are deprived of lipid synthesis ability [2], they must rely entirely on the envelope for their lipid supply. Lipid export from the inner envelope membrane (lEM) to TM is thus implicitly assumed, although this process is still largely unknown. Here, we extend our earlier study [3], now using different labelled precursors and plant species, in order to answer the following questions (1) What are the mechanism(s) of lipid export (2) Are all lipid classes and molecular species exported in the same way (3) Is the export mechanism identical among plants of different species and age ... 

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