T-antigen

A similar series of reactions was performed by Paulsen and Hdlck141 for the preparation of the T-antigenic, unprotected, amino acid-disaccha-rides 200 and 201, starting from the 4,6-0-benzylidene-N-(benzyloxy-carbonyl) benzyl esters 198 and 199, respectively, by condensation with 110 in the presence of mercury dicyanide-mercury dichloride and molecular sieves 4A, and deprotection of the product. Sinay and co-workers148 also reported the synthesis of hexa-O-acetyl derivatives of 200 and 201 by application of the sequence of azido-nitration-bromination. 

Endo, T. and Nidal-Ginard, B. (1988) SV40 large T antigen induces reentry of terminally differentiated myotubes into the cell cycle. In Kedes, L.H. and Stockdale, F.E. (eds) Cellular and Molecular Biology of Muscle Development. Alan R. Liss, New York, pp. 95-104. 

M.-G. Baek and R. Roy, Simultaneous binding of mouse monoclonal antibody and streptavidin to heterobifunctional dendritic L-lysine core bearing T-antigen tumor marker and biotin, Bioorg. Med. Chem., 9 (2001) 3005-3011. 

R. Roy, M.-G. Baek, and K. Rittenhouse-Olson, Synthesis of /V,/V -bis(acryla-mido)acetic acid base-T antigen glycodendrimers and their mouse monoclonal IgG antibody binding properties, J. Am. Chem. Soc., 123 (2001) 1809-1816. 

M.-G. Baek, K. Rittenhouse-Olson, and R. Roy, Synthesis and antibody binding properties of glycodendrimers bearing the tumor related T-antigen, Chem. Commun. (2001) 257-258. 

Protein phosphorylation is one of the most important mechanisms in the regulation of cellular function. Proteins can be phosphorylated on serine, threonine or tyrosine residues. Most phosphorylation occurs on serine and threonine, with less than 1% on tyrosine (see Ch. 23). This perhaps accounts for the late discovery of tyrosine phosphorylation, which was found first on polyoma virus middle T antigen in 1979 by Hunter and colleagues [1,2]. 

Eckhart, W., Hutchinson, M. A. and Hunter, T. An activity phosphorylating tyrosine in polyoma T antigen immunopre-cipitates. Cell 18 925-933,1979. 

A glycopeptide-BSA conjugate (150) containing the tumor-associated T-antigen structure has been constructed (44,73). 

Scheme 13.12 B chain of human a2HS glycoprotein carrying the sialyl-T-antigen.

Figure 26.1 Immortalization of human cells Cells enter replicative senescence at mortality stage 1 (Ml Hayflick limit) after about 60 population doublings (PD). The protein p 16 accumulates in senescent cells. The simian virus 40 (SV40) large T antigen as well as the human papilloma virus (HPV) type 16-E6 and E7 proteins sequester the retinoblastoma protein (Rb) and/or p53 constitutively releases the transcription factor E2F. E2F induces expression proteins required for progression through Gl/S transition, thus the cells escape cell cycle arrest. At mortality stage 2 (M2), transformed cells must overcome senescence and crisis before they are immortalized. This is likely to involve the activation of telomerase either by the introduction of hTERT cDNA or by a genetic change that activates telomerase.

Toouli, C. D., L. I. Huschtscha, A. A. Neumann, J. R. Noble, L. M. Colgin, B. Hukku, and R. R. Reddel. 2002. Comparison of human mammary epithelial cells immortalized by simian virus 40 T-Antigen or by the telomerase catalytic subunit. Oncogene 21(1) 128-39. 

Gruenert, D. C., L. Chin, E. M. Simon, and A. L. Cozens. 1990. Transformation of human airway epithelial cells with a plasmid containing a temperature-sensitive SV40 T antigen. PedPidmonol Suppl 5 146. 

Brash, D. E., R. R. Reddel, M. Quanrud, K. Yang, M. P. Farrell, and C. C. Harris. 1987. Strontium phosphate transfection of human cells in primary culture Stable expression of the simian virus 40 large-T-antigen gene in primary human bronchial epithelial cells. Mol Cell Biol 7(5) 2031-4. 

Takenouchi, T., Y. Iwamaru, M. Sato, T. Yokoyama, M. Shinagawa, and H. Kitani. 2007. Establishment and characterization of SV40 large T antigen-immortalized cell lines derived from fetal bovine brain tissues after prolonged cryopreservation. Cell Biolint 31(l) 57-64. 

Cheng, R. Z., M. A. Shammas, J. Li, and R. J. Shmookler Reis. 1997. Expression of SV40 large T antigen stimulates reversion of a chromosomal gene duplication in human cells. Exp Cell Res 234(2) 300-12. 

Redies, C., U. Lendahl, and R. D. McKay. 1991. Differentiation and heterogeneity in T-antigen immortalized precursor cell lines from mouse cerebellum. JNeurosci Res 30(4) 601-15. 

Schwartz, B., P. Vicart, C. Delouis, and D. Paulin. 1991. Mammalian cell lines can be efficiently established in vitro upon expression of the SV40 large T antigen driven by a promoter sequence derived from the human vimentin gene. Biol Cell 73(1) 7-14. 

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