Homeodomain proteins

Homeodomain proteins are involved in the development of many eucaryotic organisms... 

Eucaryotes have many more genes and a broader range of specific transcription factors than procaryotes and gene expression is regulated by using sets of these factors in a combinatorial way. Eucaryotes have found several different solutions to the problem of producing a three-dimensional scaffold that allows a protein to interact specifically with DNA. In the next chapter we shall discuss some of the solutions that have no counterpart in procaryotes. However, the procaryotic helix-turn-helix solution to this problem (see Chapter 8) is also exploited in eucaryotes, in homeodomain proteins and some other families of transcription factors. 

Homeoboxes code for homeodomains, sequences of 60 amino acids that function as the DNA-binding regions of transcription factors. Each homeo-box gene in Drosophila is expressed only in its own characteristic subset of embryonic cells, and almost every embryonic cell contains a unique combination of homeodomain proteins. 

Monomers of homeodomain proteins bind to DNA through a helix-turn-helix motif... 

TFIIA and TFIIB bind to both TBP and DNA Flomeodomain proteins are involved in the development of many eucaryotic organisms Monomers of homeodomain proteins bind to DNA through a heltx-turn-helix motif In vivo specificity of homeodomain... 

Lai, Z., Fortini, M. E., and Rubin, G. M. (1991). The embryonic expression patterns if zfh-1 and zfh-2, two Drosophila genes encoding novel zinc-finger homeodomain proteins. Mech. Dev. 34 123-134. 

Cseijesi, P., Lilly, B., Bryson, L., Wang, Y Sassoon, D., and Olson, E. (1992). MHox a mesodermally restricted homeodomain protein that binds an essential site in the muscle creatine kinase enhancer. Development 115 1087-1101. 

Odenwald, W. F, Taylor, C. E, Palmer-Hill, F. J., Friedrick, J. V., Tani, M., and Lazzarini, R. A. (1987). Expression of a homeodomain protein in noncontact-inhibited cultured cells and postmitotic neurons. Genes Dev. 1 482-496. 

Treisman, J., Gonczy, P., Vashishtha, M., Harris, E., and Desplan, C. (1989). A single amino acid can determine the DNA binding specificity of homeodomain proteins. Cell 59 553-562. 

Schindler, U., H. Beckmann, and A. R. Cashmoee, HAT3.1, a novel Arabidopsis homeodomain protein containing a conserved cysteine-rich region. Plant], 1993, 4(1), 137-50. 

Helix-turn-helix (homeodomain proteins encoded by homeotic/homeobox genes)... 

Homeodomain proteins Regulate gene expression during development Helix-turn- helix... 

Control of Cell Differentiation by Homeodomain Proteins During Development In Utero... 

Homeodomain proteins pHOX, pPAX (helix-turn-helix)... 

Answen Q Proteins with SH2 domains might bind to the insulin receptor substrate-1 (IRS-1) to transmit signals from the insulin receptor, a tyrosine kinase type of receptor. PI-3 kinase is an example of an SH2 domain protein. SH2 domains are not involved in DNA binding (choices A and D). Examples of protein domains that bind DNA include zinc fingers (steroid receptors), leudne zippers (CREB protein), and helix-turn-helbc proteins (homeodomain proteins),... 

An interesting case of regulation at the translation level was discovered on the example of the homeodomain protein bicoid (bed), which is important in Drosophila differentiation (Dubnau and Struhl, 1996). The bicoid protein is a transcriptional activator that binds a cognate DNA element and stimulates the transcription of the neighboring genes. Apart from its specific DNA-binding capabUity, the bicoid protein binds to 3 -, non-translating sequences of the mRNA of another homeodomain protein (caudal protein) to inhibit its translation. 

Dubnau,J. and Struhl, G. RNA recognition and translational regulation by a homeodomain protein (1996) Nature 379, 694-699... 

Despite intense interest the role of homeodomain proteins in development is not well understood. The highly conserved motif binds to DNA at many places in the genome. Current thinking is that homeodomain proteins interact with other regulatory proteins, and that various combinations of these proteins provide the information needed to direct development.375... 

The rapid vegative growth, which includes development of shoots, leaves, and flowers, is controlled by a variety of transcription factors.483 Among these are homeodomain proteins that control differentiation of meristem cells 484-486 The induction of flowering is... 

We tentatively conclude that the asymmetrical interaction of the homeodomain protein with DNA gives it a versa-... 

Gregory PA, Lewinsky RH, Gardner-Stephen DA, et al. Coordinate regulation of the human UDP-glucuronosyltransferase 1A8, 1A9, and 1A10 genes by hepatocyte nuclear factor lalpha and the caudal-related homeodomain protein 2. Mol Pharmacol 2004 65(4) 953-963. 

A. and Chambers, L, The homeodomain protein Nanog and pluripotency in mouse embryonic stem cells, Biochem. Soc. Trans. 33, 1518-1521, 2005 Silva, J., Chambers, L, Pollard, S., and Smith, A., Nanog promotes transfer of pluripotency afer cell fusion. Nature 441, 997-1001, 2006. 

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