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TFIIH

2011-11-28T17:36:24Z

090046986:

TFIIH is a [[General transcription factor|general transcription factor]] (GTF) involved in PIC ([[Pre-Initiation Complex|Pre-Initiation Complex]]) assembly, it is added in the last stage of assembly close to the start site of transcription. The [[Helicase|helicase]] activity of TFIIH separates the template [[DNA|DNA]] strand at the start site of [[Transcription|transcription]], forming an open complex, this requires ATP hydrolysis. TFIIH has 9 subunits and main functions include:

1. Promotor melting and clearance

2. CTD kinase activity

3. DNA repair coupling

As RNA  polymerase II begins transcribing, TFIIH is released from the complex along with TFIIB and TFIIE. 

TFIIH can be divided into two parts: core and CAK. The core section of the GTF contains several DNA helicases including XPD and XPB. XPB plays a major role in promotor melting. The CAK module can dissociated away from the TFIIH molecule where it has other functions in the cell cycle (cdk activating kinases). The CAK module also contains one of the kinases that is involved in hosphorylation of the CTD (C-terminal domain) of RNA polymerase II. This phosphorylation is needed for promotor clearance. 

Mutations in the TFIIH molecule can result in three distinct genetic diseases; 

1. Xeroderma pigmentosum 2. Trichothiodystrophy 3. Cockayne Syndrome 

TFIIH can also bind to the acidic domains of VP16 (herpes virus) and p53 (involved in apoptosis).

TFIIH

2011-11-28T17:31:09Z

090046986:

TFIIH

2011-11-28T17:27:14Z

090046986:

TFIIH is a [[General transcription factor|general transcription factor]] (GTF) involved in PIC ([[Pre-Initiation Complex|Pre-Initiation Complex]]) assembly, it is added in the last stage of assembly close to the start site of transcription. The [[Helicase|helicase]] activity of TFIIH separates the template [[DNA|DNA]] strand at the start site of [[Transcription|transcription]], forming an open complex, this requires ATP hydrolysis. TFIIH has 9 subunits and main functions include:

1. Promotor melting and clearance

2. CTD kinase activity

3. DNA repair coupling

As RNA  polymerase II begins transcribing, TFIIH is released from the complex along with TFIIB and TFIIE. 

TFIIH can be divided into two parts: core and CAK. The core section of the GTF contains several DNA helicases including XPD and XPB. XPB plays a major role in promotor melting. The CAK module can dissociated away from the TFIIH molecule where it has other functions in the cell cycle (cdk activating kinases). 

Mutations in the TFIIH molecule can result in three distinct genetic diseases; 

1. Xeroderma pigmentosum 2. Trichothiodystrophy 3. Cockayne Syndrome

TFIIH

2011-11-27T18:31:26Z

090046986: Created page with " TFIIH is a general transcription factor (GTF) involved in PIC (Pre-Initiation Complex) assembly. The helicase activity of TFIIH separates the template DNA strand at the sta..."

 TFIIH is a general transcription factor (GTF) involved in PIC (Pre-Initiation Complex) assembly. The helicase activity of TFIIH separates the template DNA strand at the start site of transcription, forming an open complex. 

ABC Superfamily

2011-11-15T09:15:35Z

090046986:

The ABC Superfamily stands for [[ATP|ATP]] Binding Cassette Family. These proteins are invloved in ion transport across the membrane, with members including [[CFTR|CFTR]] AND P-[[P- glycoprotein|Glycoprotein]]. The standard structure of a member of the ABC is 12 membrane-spanning domains and 2 [[Nucelotide Binding Domain|Nucleotide Binding Domains]] (occassionally referred to as a Nucleotide Folding Domain). ATP binds at the NBD <ref>Rees, D.C.; E. Johnson; O. Lewinson. 2009. ABC transporters: the power to change. Nat. Rev. Mol. Cell Biol. 10, 218-227.</ref>. 

The ABC family of proteins are one of the largest family of [[Proteins|proteins]] known and have been found in both [[Prokaryotes|prokaryotes]] and [[Eukaryotes|eukaryotes]]. This family of [[Proteins|proteins]] differ significantly from other ATP-binding protein family of [[Kinase|kinases]]. They are not all involved in [[Ion_channels|ion transport ]]across the [[Cell membranes|membrane]], some have also been found to be involved in the presentation of [[Antigen|antigens]] as well as being involved in different inherited human diseases .

=== ABC superfamily ===

ATP bing casettes is the membrane transport proteins which named ABC superfamily. These can be found in bacteria and human cell memberanewith different substrate. These protein is first defined by bacteria. All the plasmid cell membrane use the ion concentration gradient channel for nutrients entry or out to the cell enviroment. However, bacteria also contain energy of ATP activate substrate.

'''DISEASE'''

Single change of the mechanism in the cell can cause different effect. Abnormal function of the membrance cause different dieases. [[Cystic fibrosis|Cystic Fibrosis]] is one of the [[Gene|gene]] mutation which occurs in detaF508 in 75% of the patients.

ABC ion channel is passive tranpor in the cell membrane. There are 3 different domains precented. The transmembrane demains which forms pore in the cell membrane. 

Regulatary domains(R domains) has the same function with nucleotide binding domains(NBD) use for the gateing of the channel <ref>Bruce Alberts, A,Johnson. (fifth edition2008)"Membrane Transport of small molecules and the electrical properties of membrane" Molecular Biology of The cell.p663-6</ref>.

=== Referencesnd  ===

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