User:Hakmatnujoom/sandbox

I added general information "background" about (Transcription factors II H) and TFIIH function, how the TFIIH involved in causing various diseases.

Transcription Factor II H
Transcription Factor II H is an important protein complex, having roles in DNA nucleotide excision repair pathways and transcription of various protein-coding genes. TFIIH first came to light in 1989 when general transcription factor-δ or basic transcription factor 2 was characterized as an indispensable transcription factor in vitro. This factor was also isolated from yeast and finally named as TFIIH in 1992.

 Mammalian TFIIH  is a multiprotein complex having ten subunits that consists of two further functional sub complexes: the core complex, which is composed of six subunits (XPB), p62, p52, p44, p34 and p8); and the CAK (cyclin-dependent kinase activating kinase) complex, which is composed of CDK7, cyclin H and MAT1. The core and CAK sub complexes are joined together by the XPD subunit, which interacts with p44 and MAT1 of the core and CAK sub complexes, respectively. In nucleotide excision repair (NER), TFIIH functions to open the DNA around the area of lesion and allow the excision of the damaged oligonucleotide and then replacing it with a new DNA fragment.

TFIIH functions:
After a DNA lesion has been recognized by either the global genome repair (GGR) pathway or the transcription-coupled repair (TCR) pathway of NER. TFIIH is also responsible for transcription of ribosomal RNA (rRNA) by Pol I and in the synthesis of 5S rRNA, tRNA and other small RNAs that are transcribed by Pol III.

TFIIH involved in causing various diseases:
Genetic polymorphisms of genes that encode subunits of TFIIH (such as XPD and XPB) are known to be associated with increased cancer susceptibility in many tissues, e.g.; skin tissue, breast tissue and lung tissue. In addition to genetic variations, virus-encoded proteins also target TFIIH.