Surface Expression

Recent studies indicate that - like many other receptors - G-protein-coupled receptors may form dimers, either homodimers or dimers with another type of receptor. The role of dimer formation in the cell surface expression of receptors and in their signalling and the resultant pharmacology are currently under intensive investigation [1]. 

A process in which a substance gains entry into a cell. Endocytic mechanisms are crucial for a variety of cellular functions such as the uptake of nutrients, regulation of cell surface expression of receptors, maintenance of cell polarity, and more. Receptor-mediated endocytosis via clathrin-coated pits is the most studied endocytic process, which is important for regulation of the time and magnitude of signals generated by a variety of cell-surface receptors. 

PAMPs and various tissue factors can prime DCs to produce T-cell-polarizing factors [21], IL-12 is a pro-inflammatory cytokine that induces IFN-y and promotes the development of Thl-cell differentiation [31], Other Thl-polarizing factors are IFN-a and IFN-(3 [32] and cell-surface expressed intracellular adhesion molecule (ICAM)-l [33]. On the other hand, it has been shown that NF-kB inducing kinase (NIK), which is known to regulate B-cell maturation and lymphoid organogenesis, is important for the induction of Thl7 cells [34],... 

Kalesnikoff J. Rios EJ, Chen CC, Alejandro Barbieri M. Tsai M. Tam SY, Galli SJ Roles of RabGEFl/ Rabex-5 domains in regulating FccRI surface expression and FceRI-dependent responses in mast cells. Blood 2007 109 5308-5317. 

HFE has been shown to be located in cells in the crypts of the small intestine, the site of iron absorption. There is evidence that it associates with P2 niicroglobu-lin, an association that may be necessary for its stability, intracellular processing, and cell surface expression. The complex interacts with the transferrin receptor (TfR) how this leads to excessive storage of iron when HFE is altered by mutation is under close smdy. The mouse homolog of HFE has been knocked out, resulting in a potentially useful animal model of hemochromatosis. 

Bruhl H, Wagner K, Kellner H, Schattenkirchner M., Schlondorff D, Mack M. Surface expression of CC- and CXC-chemokine receptors on leucocyte subsets in inflammatory joint diseases. Clin Exp Immunol 2001 126 551-559. 

Aksoy MO, Yang Y, Ji R, et al. CXCR3 Surface expression in human airway epithelial cells cell cycle dependence and effect on cell proliferation. Am J Physiol Lung Cell Mol Physiol 2005 290(5) L909-918. 

Of the four markers just mentioned, the expression of P-selectin on the activated platelets is the most widely studied. However, CD62P may not be the ideal marker for detection of circulating degranulated platelets, because they may rapidly lose their surface P-selectin but yet may continue to function. The decrease in the platelet surface expression of the GPIb-IX-V complex (CD42) perhaps represents a more sensitive marker of in vivo platelet activation. Apparently platelet activation related to strenuous exercise is more readily detected using CD42 than other markers (99). 

N-Glycosylation secures folding and cell surface expression. 

Daws L., Callaghan P., Morom J. et al. Cocaine increases dopamine uptake and cell surface expression of dopamine transporters. Biochem. Biophys. Res. Commun. 290 1545, 2002. 

Park, M. and Tenner, A.J. (2003) Cell surface expression of ClqRP/CD93 is stabilized by O-glycosylation. Journal of Cellular Physiology, 196 (3), 512—522. 

Sickle erythrocytes have increased surface expression of CD36. Microvascular endothelial cells do express CD36. Adhesion between these CD36 molecules of the two cells types can be mediated via the bridging ligand thrombospondin". Indeed plasma thrombospondin levels are increased in SCA patients with pain crisis [15]. 

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