Constitutive transport

Bear, J., Tan, W., Zolotukhin, A.S., Tabemero, C., Hudson, E.A. and Felber, B.K. (1999) Identification of novel import and export signals of human TAP, the protein that binds to the constitutive transport element of the type D retrovirus mRNAs. Mol. Cell. Biol., 19, 6306-6317. 

Bogerd, H.P., Echarri, A, Ross, T.M. and Cullen, B.R. (1998) Inhibition of human immunodeficiency virus Rev and human T-cell leukemia virus Rex function, but not Mason-Pfizer monkey virus constitutive transport element activity, by a mutant human nucleoporin targeted to Crml. J. Virol, 72, 8627-8635. 

Braun, I.C., Rohrbach, E., Schmitt, C. and Izaurralde, E. (1999) TAP binds to the constitutive transport element (CTE) through a novel RNA-binding motif that is sufficient to promote CTE-dependent RNA export from the nucleus. EMBOJ., 18, 1953-1965. 

Ernst, R.K., Bray, M., Rekosh, D. and Hammarskjold, M.-L. (1997a) Secondary structure and mutational analysis of the Mason-Pfizer monkey virus constitutive transport element. RNA, 3,219-222. 

Kang, Y., Bogerd, H P., Yang, J. and Cullen, B.R. (1999) Analysis of the RNA binding specificity of the human TAP protein, a constitutive transport element-specific nuclear RNA export factor. Virology, 262, 200-209. 

Mautino, M.R., Reiser, N. and Morgan, R.A. (2000) Improved titers of HIV-based lentiviral vectors using the SRV-1 constitutive transport element. Gene Ther., 7,1421-1424. 

Saavedra, C., Felber, B. and Izauralde, E. (1997) The simian retrovirus-1 constitutive transport element, unlike the HIV-1 RRE, uses factors required for cellular mRNA export. Curr. Biol, 7, 619-628. 

Discrepancies between reactive and adsorption surface area may also be related to the presence of deep etch pits or pore outcrops which can constitute transport-limited micro-environments for dissolution (Jeschke and Dreybrodt, 2002). Much of the BET surface area for some alkali feldspars used for dissolution in the laboratory has been attributed to grinding-induced microporosity (Hodson et al, 1999), and such pore outcrops are candidates for transport limitation. If such induced surfaces react dilferently than surfaces of weathered samples, then the BET surface area may be an inappropriate parameter to use for extrapolating interface-limited kinetics from laboratory to field (Lee et al, 1998 Brantley and Mellott, 2000 Jeschke and Dreybrodt, 2002) and consideration may need to be given to length and extent of grinding for laboratory samples (Hodson, 1999). It may be more appropriate to use geometric rather than BET surface area to extrapolate kinetics for samples where etch pits or pore outcrops are important contributors to BET surface area (Gautier et al, 2001 Jeschke and Dreybrodt, 2002 Mellott et al, 2002). 

A distinctive characteristic of physicochemical hydrodynamics is the commonality of behaviors underlying many seemingly diverse phenomena. The commonality is brought about by two factors (1) the similar character of the continuum, linear constitutive transport relations for mass, heat, and charge (2) the similarity or, frequently, the identity of boundary conditions for chemical, electrochemical, and biochemical reactions mass, charge, and heat transfer and phase change. Throughout the book we shall attempt to exploit the behavioral similarities of these different physical and chemical phenomena. 

Zolotukhin, A. S., Michalowski, D., Smulevitch, S., Felber, B. K. (2001). Retroviral constitutive transport element evolved from cellular TAP(NXFl)-binding sequences. J Virol 75, 5567-5575. 

A surprisingly high number of carriers are present constitutively in the cytoplasmic membrane. One may speculate about the advantages for bacteria to possess always carriers for several solutes. Possibly the possession of constitute carriers would enable an organism to scavenge intermediates leaked passively out of the cell and/or allow the organism to react rapidly to changes in the external medium. Besides constitutive transport systems inducible transport systems are also found in bacteria such as those for lactose transport in E. coli or for citrate transport in B. subtilis. 

To bridge the gap between molecular and macroscopic scales, models based on statistical mechanics can be formulated in terms of molecular parameters obtained from rigorous ab initio calculations (in principle) or from experiments as empirical parameters (the usual practice). Using molecular parameters as inpuf statistical mechanical models yield (1) estimates of constitutive transport coefficients required for continuum models, and (2) important physical insight necessary for formulating realistic, useful continuum models. 

In the vehicle mechanism the proton is transported as a passenger on an oxide ion. Thus this mechanism may be considered to constitute transport of hydroxide ions. The hydroxide ion may in principle move by an oxygen vacancy mechanism or as an interstitial hydroxide ion. It may be noted that the hydroxide... 

The theory coimecting transport coefficients with the intemiolecular potential is much more complicated for polyatomic molecules because the internal states of the molecules must be accounted for. Both quantum mechanical and semi-classical theories have been developed. McCourt and his coworkers [113. 114] have brought these theories to computational fruition and transport properties now constitute a valuable test of proposed potential energy surfaces that... 

The bipolar junction transistor (BIT) consists of tliree layers doped n-p-n or p-n-p tliat constitute tire emitter, base and collector, respectively. This stmcture can be considered as two back-to-back p-n junctions. Under nonnal operation, tire emitter-base junction is forward biased to inject minority carriers into tire base region. For example, tire n type emitter injects electrons into a p type base. The electrons in tire base, now minority carriers, diffuse tlirough tire base layer. The base-collector junction is reverse biased and its electric field sweeps tire carriers diffusing tlirough tlie base into tlie collector. The BIT operates by transport of minority carriers, but botli electrons and holes contribute to tlie overall current. 

Shale oil contains large quantities of olefinic hydrocarbons (see Table 8), which cause gumming and constitute an increased hydrogen requirement for upgrading. Properties for cmde shale oil are compared with petroleum cmde in Table 10. High pour points prevent pipeline transportation of the cmde shale oil (see Pipelines). Arsenic and iron can cause catalyst poisoning. 

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