In the thick segment of the ascending loop of Henle, paracellular reabsorption of cations, such as Mg++, Ca++, Na+, and K+ occur

TLS Online TPP Program

#Id: 1987

#Unit 3. Fundamental Processes

The 5’ cap of most mRNA is monomethylated, but some small noncoding RNAs are trimethylated.

TLS Online TPP Program

#Id: 1988

#Unit 3. Fundamental Processes

Small ncRNAs involved in RNA splicing in the spliceosome are trimethylated at terminal guanine. This structure is called a trimethylated cap. The enzymes for these additional methyl transfers are present in the cytoplasm.

TLS Online TPP Program

#Id: 1989

#Unit 3. Fundamental Processes

SL RNA (Trans-splicing) carries a trimethylated cap, which is recognized by the variant cap-binding factor eIF4E to facilitate translation.

TLS Online TPP Program

#Id: 1990

#Unit 3. Fundamental Processes

The sequence AAUAAA (hexamer) is a signal for cleavage to generate a 3’ end of mRNA that is polyadenylated.

TLS Online TPP Program

#Id: 1991

#Unit 3. Fundamental Processes

Polyadenylation requires a protein complex that contains a specificity factor, an endonuclease, and poly(A) polymerase.

 

TLS Online TPP Program

#Id: 1992

#Unit 3. Fundamental Processes

Binding of polyadenylation factors takes place when CTD Ser2 phosphorylated.