Differences in cell-to-cell and cell-to-matrix adhesions as well as the cell density within the niche can alter the mechanical forces that influence stem cell behavior.

TLS Online TPP Program

#Id: 1852

#Unit 3. Fundamental Processes

The CTD contains a series of repeats of the heptapeptide sequence: Tyr-Ser-Pro-Thr-Ser-Pro-Ser. 

TLS Online TPP Program

#Id: 1853

#Unit 3. Fundamental Processes

There are 27 of these repeats in the yeast Pol II CTD, 32 in the worm Caenorhabditis elegans, 45 in the fly Drosophila, and 52 in humans. 

YSPTSPS repeats in CTD corresponds to the complexity of the genome.

TLS Online TPP Program

#Id: 1854

#Unit 3. Fundamental Processes

Class II promoters have two parts:

Core promoter having 4 elements

Upstream promoter element

TLS Online TPP Program

#Id: 1855

#Unit 3. Fundamental Processes

Start point, is the first base of mRNA to be A

• Initiator (Inr) is Py2CAPy5, where Py stands for any pyrimidine. The Inr is contained between positions -3 and +5.

• TATA box, usually located, 25 bp upstream in its location at -25

• The exception is in yeast, where the TATA box is more typically found at -90.

TLS Online TPP Program

#Id: 1856

#Unit 3. Fundamental Processes

Promoters that do not contain a TATA element are called TATA-less promoters. Surveys of promoter sequences suggest that 50% or more of promoters may be TATA-less.

TLS Online TPP Program

#Id: 1857

#Unit 3. Fundamental Processes

Constitutive active housekeeping genes and developmentally regulated genes have TATA-less promoters.