- How do endoribonucleases (ERNs) work to decrease protein levels? Name 2 differences between how ERNs work and how proteases work.
In bacteria, the 5′-end dependent mechanism for mRNA degradation has been described
**5′-end dependent RNA degradation**
Initiation of degradation
- A typical primary transcript possesses a single stranded, triphosphorylated 5′-terminus and a 3′-end with a stem–loop structure.
- Prior to internal cleavage by RNase E there is an RppH-dependent pyrophosphate removal step at the 5′-terminus
Internal cleavage by RNase E
- Internal, endonucleolytic cleavages are performed by RNase E, which requires the monophosphorylated 5′-end for catalytic activity.
- The monophosphorylated 5′-fragment is then subject to further endonucleolytic cleavages or 3′-5′ exonucleolytic decay by exoribonucleases such as RNase II, RNase R, and PNPase.
- How does lipofectamine 3000 work? How does DNA get into human cells and how is it expressed?
Lipofectamine 3000 is a synthetic lipid vector. The mechanism of action of this compound involves three steps:
- Step 1: Lipofectamine 3000 forms a complex with nucleic acids, which binds to the cell and enters via endocytosis
- Step 2: Once inside the cell, an endosome is formed, which, due to the action of Lipofectamine 3000, does not mature, thereby preventing the degradation of nucleic acids.
- Step 3: Finally, nucleic acids are released from the endosome and directed to the cell nucleus
