Scaffold Attachment Region

Fig. 2. Scaffold attachment regions (SAR) flanking soybean hs genes. The sequences of the small soybean hs genes were screened for the presence of scaffold binding sequences , Drosophila A-box consensus AATAAA(TC)AAA , T-box consensus TT(AT)T(TA)TT(TA)TT (Gasser Laemmli, 1986) , topoisomerase II consensus...

Klehr, D., Maass, K. and Bode, J. (1991) Scaffold-attached regions from the human interferonbeta domain can be used to enhance the stable expression of genes under the control of various promoters. Biochemistry, 30, 1264-1270. 

Bode, J., and Maass, K. (1988). Chromatin domain surrounding the human interferon-/3 gene as defined by scaffold-attached regions. Biochemistry 27, 4706-4711. 

Gohring F, Fackelmayer FO (1997) The scaffold/matrix attachment region binding protein hnRNP-U (SAF-A) is directly bound to chromosomal DNA in vivo a chemical cross-linking study. Biochemistry 36(27) 8276-8283... 

The DNA of a bacterial cell, such as Escherichia coli, is a circular double-stranded molecule often referred to as the bacterial chromosome. In E. coli this DNA molecule contains 4.6 million base pairs. The circular DNA is packaged into a region of the cell called the nucleoid (see Topic Al) where it is organized into 50 or so loops or domains that are bound to a central protein scaffold, attached to the cell membrane. Fig. la illustrates this organization, although only six loops are shown for clarity. Within this structure, the DNA is actually not a circular double-stranded DNA molecule such as that shown in Fig. lb but is negatively supercoiled, that is, it is twisted upon itself (Fig. lc) and is also complexed with several DNA-binding proteins, the most common of which are proteins HU, HLP-1 and H-NS. These are histone-like proteins (see below for a description of histones). 

Scaffold and matrix attachment region Smooth mnscle cell... 

Girod, P.-A. and Mermod, N. (2003) Use of scaffold/matrix-attachment regions for protein production. In S.C. Makrides (Ed) Gene transfer and expression in mammalian cells. Elsevier Science B.V., pp. 359-379. 

In situ hybridization experiments with several different fluorescent-labeled probes to DNA in human Interphase cells support the loop model shown in Figure 10-24. In these experiments, some probe sequences separated by millions of base pairs in linear DNA appeared reproducibly very close to one another in interphase nuclei from different cells (Figure 10-25). These closely spaced probe sites are postulated to lie close to specific sequences in the DNA, called scaffold-associated regions (SARs) or matrix-attachment regions (MARs), that are bound to the chromosome scaffold. SARs have been mapped by digesting histone-depleted chromosomes with restriction enzymes and then recovering the fragments that are bound to scaffold proteins. 

Describe the general organization of a eukaryotic chromosome. What structural role do scaffold associated regions (SARs) or matrix attachment regions (MARs) play Where are genes primarily located relative to chromosome structure ... 

The nuclear matrix. The lipid bilayers, the histones and other soluble proteins, and the DNA can all be removed from nuclei by extraction and enzymatic digestion. An insoluble residue, the nuclear matrix, is left. " Largely protein in nature, this matrix is spread throughout the nucleus. Remnants of the membranes remain in the form of proteins that were in or along the bilayer. The nucleolus is clearly defined. The DNA appears to be bound to the nuclear matrix proteins. A specific 320-kb piece of a Drosophila chromosome has been mapped and used to locate nontran-scribed scaffold (or matrix) attachment regions of DNA bound to matrix proteins. These were found at intervals of 26-112 kb, the intervening loops containing up to five or more A 120-kDa... 

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