What does P-TEFb do?
P-TEFb is a cyclin dependent kinase that can phosphorylate the DRB sensitivity inducing factor (DSIF) and negative elongation factor (NELF), as well as the carboxyl terminal domain of the large subunit of Pol II and this causes the transition into productive elongation leading to the synthesis of mRNAs.
What is the role of P-TEFb during elongation?
The positive transcription elongation factor b (P-TEFb) is a cyclin-dependent kinase that controls the elongation phase of transcription by RNA polymerase II (RNAPII). In complex organisms, elongation control is critical for the regulated expression of most genes.
What are DSIF and NELF?
DSIF is a heterodimer composed of Spt4 and Spt5, and NELF is a protein complex composed of four subunits (A, B, C/D, and E). These factors cooperatively induce transcriptional pausing by binding to initiated Pol II and possibly also to newly synthesized transcript [20], [26], [27].
What is 7SK?
In molecular biology 7SK is an abundant small nuclear RNA found in metazoans. It plays a role in regulating transcription by controlling the positive transcription elongation factor P-TEFb.
What are the targets of P-TEFb phosphorylation?
The kinase activity of P-TEFb is required in all assays requiring P-TEFb function, but there is more than one possible target for phosphorylation. The evidence suggests very strongly that the CTD of the large subunit of RNA polymerase II is the important physiological target.
What is elongation transcription?
Transcription elongation is a regulated process in which an RNA chain complementary to the template strand of DNA is synthesized as RNA polymerase moves along DNA. Transcription elongation is preceded by transcription initiation and is followed by transcription termination.
What do snRNPs do?
snRNPs mainly function as core components of the spliceosome, the molecular machinery for pre-mRNA splicing. Thus, snRNP biogenesis is a critical issue for plants, essential for the determination of a cell’s activity through the regulation of gene expression.
Does cyclin phosphorylate CDK?
Cyclins are a family of proteins that have no enzymatic activity of their own but activate CDKs by binding to them. CDKs must also be in a particular phosphorylation state — with some sites phosphorylated and others dephosphorylated — in order for activation to occur.
What enzyme is used for elongation transcription?
RNA polymerase
During elongation, RNA polymerase “walks” along one strand of DNA, known as the template strand, in the 3′ to 5′ direction. For each nucleotide in the template, RNA polymerase adds a matching (complementary) RNA nucleotide to the 3′ end of the RNA strand.
What are the 3 stages of transcription?
It involves copying a gene’s DNA sequence to make an RNA molecule. Transcription is performed by enzymes called RNA polymerases, which link nucleotides to form an RNA strand (using a DNA strand as a template). Transcription has three stages: initiation, elongation, and termination.
Are Spliceosomes enzymes?
The spliceosome is an enzyme in pieces, and thus to fit the strict definition of an enzyme, these pieces must be regenerated so that they may catalyze multiple rounds of pre-mRNA splicing.
What is difference between spliceosome and snRNPs?
snRNPs (pronounced “snurps”), or small nuclear ribonucleoproteins, are RNA-protein complexes that combine with unmodified pre-mRNA and various other proteins to form a spliceosome, a large RNA-protein molecular complex upon which splicing of pre-mRNA occurs.