suter2@urz.unibas.ch (clemens suter-crazzolara) (02/14/91)
dear colleagues, we have cloned a rna gene of 1100 bp. this gene contains 4 stretches of at least 10 A or 10 T residues, one of them located between enhancer and promoter. does anyone know whether these A or T rich stretches have a function, or how they have arisen ? can they influence transcription ? The gene is probably transcribed by PolII and it is mammalian. thanks, clemens (or do I have to sign "woof" ?????)
elliston@av8tr.UUCP (Keith Elliston) (02/16/91)
In article <60*.S=suter2.OU=urz.O=unibas.PRMD=SWITCH.ADMD=ARCOM.C=CH.@MHS>, suter2@urz.unibas.ch (clemens suter-crazzolara) writes: > dear colleagues, > we have cloned a rna gene of 1100 bp. this gene contains 4 stretches of at least > 10 A or 10 T residues, one of them located between enhancer and promoter. > does anyone know whether these A or T rich stretches have a function, > or how they have arisen ? can they influence transcription ? > The gene is probably transcribed by PolII and it is mammalian. > Check out Biochemistry 29:6161-6171 (1990) by Chan et al. the paper is titled "Physical Studies of DNA premelting equilibria in duplexes with and without homo dA:dT Tracts: Correlations with DNA bending." The authors talk about a "premelting" that occurs in stretches of DNA that are poly dA, poly dT. This premelting occurs at 37 C. and may be involved in the disruption of "bent" DNA. The authors also speculate that these poly dA poly dT stretches may be involved in ligand binding at these poly dA poly dT sites. Other refs to look at may be: Breslauer et al. (1987) Proc. Natl. Acad. Sci. USA 84:8922-8926. Herrera and Chaires (1989) Biochemistry 28:1993-2000. Good luck... Keith Elliston -- Keith O. Elliston elliston@av8tr.UUCP elliston@msdrl.com AA5A N9734U elliston@mbcl.rutgers.edu elliston@biovax.bitnet "Fly because you have to, to keep some semblance of sanity."
suter2@urz.unibas.ch (clemens suter-crazzolara) (02/18/91)
dear netters a w few days back i asked whether anybody had an explanation for the occurence of a/t stretches in the upstream and downstream regions of a small rna gene (mammalian) that we have cloned. our gene contains five such stretches, each about 11 bp long, one is located between promoter and enhancer. i recieved several hints what their function could be: one of these was that they play a role in transcription (that is, they function as regions that have promoter activity, or regions that are easily melted). What i did not stress (and i should have, foolish me) is that these stretches consist of 10 As or 10 Ts *exclusively*, that is they resemble the A or T stretches found in cDNA clones (resulting from polyadenylation). as a matter of fact, after obtaining a clone, my first impression was that we were dealing with a pseudogene. Did any of you see these a *or* t stretches before (this was my question, and still is) and do any of you know there function and/or origin ? i am greatful for any hint to their nature ! thanks, clemens