When bound to the ribosome, stringent factor catalyzes formation of the unusual nucleotide guanosine tetraphosphate (ppGpp); it adds pyrophosphate to the 3 position of GTP, in the reaction.

TLS Online TPP Program

#Id: 6125

#Unit 3. Fundamental Processes

Humans have the enzyme hSMUG1, which removes any U residues that occur in single-stranded DNA during replication or transcription.  Two other human DNA glycosylases, TDG and MBD4, remove either U or T residues paired with G, generated by deamination of cytosine or 5-methylcytosine, respectively.

TLS Online TPP Program

#Id: 5051

#Unit 3. Fundamental Processes

DnaA ATPase activity is stimulated by membrane phospholipids and single-stranded DNA.

TLS Online TPP Program

#Id: 1615

#Unit 4. Cell Communication and Cell Signaling

C-type lectin receptor CLRs are plasma membrane receptors expressed variably on monocytes, macrophages, dendritic cells, neutrophils, B cells, and T-cell subsets.

TLS Online TPP Program

#Id: 596

#Unit 2. Cellular Organization

When DNA is extensively damaged (such as by UV light. RecA protein binds to this damaged, single-stranded DNA, activating the protein's coprotease activity. While bound to DNA, the RecA protein facilitates cleavage and inactivation of the Lex and Lambda repressor. 

TLS Online TPP Program

#Id: 9085

#Unit 4. Cell Communication and Cell Signaling

Subunit B recognizes and binds to specific gangliosides on the surface of intestinal epithelial cells and provides a route for subunit A to enter.