Retinoblastoma
The retinoblastoma families of proteins are key cell cycle regulatory molecules important for the differentiation of various mammalian cell types. The retinoblastoma protein (RB) regulates transcription of a variety of genes either by blocking the activation domain of various activators or by active repression (finding of appropriate promoters). If the RB?s function is lost, it will lead to a variety of cancers and defects in the development of certain cell types. Phosphorylation of RB by cyclin and cyclin-dependent kinases leads to dissociation of RB from E2F (protein receptor), allowing progression into the S-phase. RB has also been proven to have the ability to block cell cycle progression from G1- to the S-phase. (Chan et al, 2001)RB is also a general tumor suppressor, which is associated with a central N (A/B) and C-terminal (pocket domains, which are binding sites for RB) that were defined to have the ability to bind cellular and viral proteins that affect the cell division cycle. Mutations in the pocket domain region are often tumorigenic. These pocket domains are also present in homologues structures of RB that exhibit similar protein binding and functional characteristics pertaining to the cell division cycle. Even
Mediated transcription is also controlled by the interaction of aromatic hydrocarbon receptor (AHR) and RB. AHR is an 805-amino acid-long ligand-activated transcription factor. When AHR forms a complex and synergizes with RB it represses E2F-dependent transcription and cell cycle progression. AHR by itself possesses none of these functions; their main role is to interact with RB by lowering the amount of RB required to achieve a certain effect. (Puga et al., 2000) The functions of NR, GR, and AHR all deal with the N-terminal. These receptors are significant, to an extent that concludes further studies must be conducted on towards the N-terminal. The main role of the N-terminal is still an uncertainty. Their role in binding with RB is anonymity. No factors that might bind RB solely with the N-terminal domain, but it is clear that the total structural information of the domain determines its efficacy because the entire N-terminal domain is necessary. (Puga et al, 2000) Both of these receptors have an N-terminal A/B region, which contains the activity activation function that activates transcription constitutively. They also include a C-terminal that contains the ligand-binding domain (LBD). In Ligand-dependent gene expression mediated by NRs involves the displacement of co repressors and subsequent conscription of transcriptional
Some common words found in the essay are:
A/B C-terminal, LBD Ligand-dependent, RB AHR, AHR RB, , S-phase GR, GR AHR, N-terminal A/B, NR GR-, S-phase Chan, et al, al 2001, et al 2001, cell cycle, et al 2000, puga et, puga et al, al 2000, chan et, cycle progression, rb critical, singh et al, singh et, cell division cycle, division cycle,
Approximate Word count = 912
Approximate Pages = 4 (250 words per page double spaced)
|
