TEL04R-XR, the X element combinatorial repeat region on the right arm of chromosome IV, spans 280 bp and contains repeats of the D, C, B and A types, Tbf1p binding sites, and dubious ORF YDR544C.

Formerly known as subtelomeric repeats or STRs, X element combinatorial repeats are generally between 250 and 300 bp long and are located between the X element core sequence and the telomeric end (1). X element combinatorial repeats are usually present as a combination of one or more of several types of smaller elements designated D, C, B, or A, with D types being most proximal to the centromere, followed by C types and so on (2). Most X element combinatorial repeat regions contain Tbf1p binding sites, and possible functions include a role in telomerase-independent telomere maintenance via recombination or as a barrier against transcriptional silencing (2).

Other features of TEL04R, the right telomeric region of chromosome IV, include an X element core sequence TEL04R-XC, a short stretch of telomeric repeats TEL04R-TR, and a long Y' (Y'-L) element TEL04R-YP.

Click on the following figure for more details:

Further information can be found at the website of Dr. Ed Louis, Institute of Genetics, The University of Nottingham.

Last updated: 2003-11-07