Transcription termination RNA polymerase I terminates transcription at

  • Slides: 51
Download presentation
Transcription termination • RNA polymerase I terminates transcription at an 18 base terminator sequence.

Transcription termination • RNA polymerase I terminates transcription at an 18 base terminator sequence. • RNA polymerase III terminates transcription in poly(U)4 sequence embedded in a G·C-rich sequence. • In pol II transcripts the sequence AAUAAA is a signal for cleavage to generate a 3 end of m. RNA that is polyadenylated.

RNA polymerasi II termination • The reaction requires a protein complex that contains a

RNA polymerasi II termination • The reaction requires a protein complex that contains a specificity factor, an endonuclease, and poly(A) polymerase. • The specificity factor and endonuclease cleave RNA downstream of AAUAAA. • The specificity factor and poly(A) polymerase add ~200 A residues processively to the 3 end.

Fosforilazione della coda CTD Watson et al. , BIOLOGIA MOLECOLARE DEL GENE, Zanichelli editore

Fosforilazione della coda CTD Watson et al. , BIOLOGIA MOLECOLARE DEL GENE, Zanichelli editore S. p. A. Copyright © 2005

Fosforilazione della coda CTD Watson et al. , BIOLOGIA MOLECOLARE DEL GENE, Zanichelli editore

Fosforilazione della coda CTD Watson et al. , BIOLOGIA MOLECOLARE DEL GENE, Zanichelli editore S. p. A. Copyright © 2005

“Fabbrica dell’RNA” (RNA factory) • Interdipendenza trascrizione e modificazioni post-trascrizionali • Pol II senza

“Fabbrica dell’RNA” (RNA factory) • Interdipendenza trascrizione e modificazioni post-trascrizionali • Pol II senza CTD inibisce splicing, terminazione e poliadenilazione • CPSF e Cst. F legano il CTD • CPSF si trova associato a TFIID

Splicing del gene Dscam Watson et al. , BIOLOGIA MOLECOLARE DEL GENE, Zanichelli editore

Splicing del gene Dscam Watson et al. , BIOLOGIA MOLECOLARE DEL GENE, Zanichelli editore S. p. A. Copyright © 2005

Complessità genoma-proteoma • Percentuale di geni con splicing alternativo varia tra 35 e 59

Complessità genoma-proteoma • Percentuale di geni con splicing alternativo varia tra 35 e 59 • Il gene Dscam di Drosofila (recettore per la guida degli assoni) contiene 95 possibili esoni che fanno splicing alternativo per un totale di 38000 isoforme proteiche possibili • Il 15% delle mutazioni che causano malattie genetiche provocano difetti di splicing

Watson et al. , BIOLOGIA MOLECOLARE DEL GENE, Zanichelli editore S. p. A. Copyright

Watson et al. , BIOLOGIA MOLECOLARE DEL GENE, Zanichelli editore S. p. A. Copyright © 2005

Watson et al. , BIOLOGIA MOLECOLARE DEL GENE, Zanichelli editore S. p. A. Copyright

Watson et al. , BIOLOGIA MOLECOLARE DEL GENE, Zanichelli editore S. p. A. Copyright © 2005

tra sxl dsx

tra sxl dsx

Alternative splicing • Specific exons may be excluded or included in the RNA product

Alternative splicing • Specific exons may be excluded or included in the RNA product by using or failing to use a pair of splicing junctions. • Exons may be extended by changing one of the splice junctions to use an alternative junction. • Alternative splicing may depend on SR proteins or specific factors

Ruolo della poliadenilazione alternativa • stabilità dell'm. RNA • localizzazione dell'm. RNA • espressione

Ruolo della poliadenilazione alternativa • stabilità dell'm. RNA • localizzazione dell'm. RNA • espressione di proteine diverse • regolazione della traduzione

Figure 2. Regulation of Immunoglobulin Expression Low affinity binding of Cst. F to the

Figure 2. Regulation of Immunoglobulin Expression Low affinity binding of Cst. F to the upstream ms site is indicated by a hatched pattern.

Scelta del sito di poliadenilazione • Sequenze cis-agenti che definiscono il sito di taglio

Scelta del sito di poliadenilazione • Sequenze cis-agenti che definiscono il sito di taglio • Concentrazione o attività dei fattori costitutivi di poliadenilazione • Espressione di fattori specifici di poliadenilazione e fattori di splicing

Poro nucleare • Il complesso del poro nucleare (NPC) è grande 125 MDa (66

Poro nucleare • Il complesso del poro nucleare (NPC) è grande 125 MDa (66 MDa in lievito) • 2000 NPC nei vertebrati (200 in lievito) • NPC è composto da circa 1000 proteine di 30 -50 tipi diversi (di ciascuna almeno 8 copie) • Molecole fino a 9 nm (30 -40 k. Da) diffondono liberamente attraverso l’NPC • Molecole fino a 25 nm vengono attivamente trasportate attraverso l’NPC

Substrato Carrier

Substrato Carrier

Transport through the nuclear pores • The NLS and NES consist of short sequences

Transport through the nuclear pores • The NLS and NES consist of short sequences that are necessary and sufficient for proteins to be transported through the nuclear pores. • Transport receptors have the dual properties of recognizing NLS or NES sequences and binding to the nuclear pore. • The direction of transport is controlled by the state of the monomeric G protein, Ran. • The nucleus contains Ran-GTP, which stabilizes export complexes, while the cytosol contains Ran-GDP, which stabilizes import complexes. • The mechanism of movement does not involve a motor.

Transcription termination RNA polymerase I terminates transcription atTranscription termination RNA polymerase I terminates transcription at
Transcription DNA RNA Transcription polymerase factors 1 activeTranscription DNA RNA Transcription polymerase factors 1 active
Transcription Translation DNA RNA polymerase RNA nucleotides ATPTranscription Translation DNA RNA polymerase RNA nucleotides ATP
RNA polimerasi eucariotiche RNA polymerases RNA polymerase IRNA polimerasi eucariotiche RNA polymerases RNA polymerase I
RNA Transcription RNA vs DNA RNA Contains AdenineRNA Transcription RNA vs DNA RNA Contains Adenine
TRANSCRIPTION RNA CLASSIFICATION ribosomal RNA r RNA messengerTRANSCRIPTION RNA CLASSIFICATION ribosomal RNA r RNA messenger
RNA TRANSCRIPTION TRANSLATION RNA RNA ribonucleic acid CarriesRNA TRANSCRIPTION TRANSLATION RNA RNA ribonucleic acid Carries
RNA and Transcription DNA RNA PROTEIN RNA andRNA and Transcription DNA RNA PROTEIN RNA and
t RNA t RNA Transfer RNA t RNAt RNA t RNA Transfer RNA t RNA
RNA RNA RNA ribonucleic acid RNA is aRNA RNA RNA ribonucleic acid RNA is a
RNA m RNA informacijska RNA r RNA ribosomskaRNA m RNA informacijska RNA r RNA ribosomska
Transcription 5 3 direction RNA polymerase consensus sequenceTranscription 5 3 direction RNA polymerase consensus sequence
Mechanisms of Transcription RNA polymerase does not needMechanisms of Transcription RNA polymerase does not need
Transcription and RNA DNA polymerase Replication DNA copiedTranscription and RNA DNA polymerase Replication DNA copied
Transcription and Translation 1201 120320 RNA polymerase IITranscription and Translation 1201 120320 RNA polymerase II
Transcription in Prokaryotes RNA Polymerase RNAP Prokaryotes ETranscription in Prokaryotes RNA Polymerase RNAP Prokaryotes E
RNA Polymerase Binding and Initiation of Transcription PromotersRNA Polymerase Binding and Initiation of Transcription Promoters
Gene Discovery The Central Dogma Transcription RNA polymeraseGene Discovery The Central Dogma Transcription RNA polymerase
rd 3 RTPCR RNA REVERSE TRANSCRIPTION POLYMERASE CHAINrd 3 RTPCR RNA REVERSE TRANSCRIPTION POLYMERASE CHAIN
General Principles De novo initiation RNA polymerase RNAGeneral Principles De novo initiation RNA polymerase RNA
RNA polymerase 1 General properties E coli RNARNA polymerase 1 General properties E coli RNA
Oversikt RNA polymerase I proteinfaktorer og promotergenorganisering RNAOversikt RNA polymerase I proteinfaktorer og promotergenorganisering RNA
RNA Polymerase III Class I 5 S RNARNA Polymerase III Class I 5 S RNA
Prokaryotic Transcription Both Eukaryotic Transcription Prokaryotic Transcription 1Prokaryotic Transcription Both Eukaryotic Transcription Prokaryotic Transcription 1