usmle_exam2005
Forum Newbie
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I think B. transcription factor
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| reet
Forum Fanatic
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TRANSCRIPTION FACTOR... TRUE
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Live as u were to die tommorow. Learn as if u were to live forever.
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| mixo
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b
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| KEROCHI
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vgood guys, that's the rt. ans.
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| mildus
Forum Guru
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receptors for steroids (cortizol, aldosteron, sex hormons, calcitriol), thyroid hormons and vitA act as transcription factors
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| krsna
Forum Senior
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aren't they called the zinc finger proteins??jus makin sure guys
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| mildus
Forum Guru
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yes because they contain Zn
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| mitali
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that's very useful info, guys. here is what I've understood in the whole thing so far, correct me if i am wrong: lipid soluble hormones like the steroid hormones can directly enter the cell membrane ( hydrophobic exterior) and go to their receptors - cytoplasm. the idea is to generate new proteins. The sequence for this is: DNA replication; forming RNA from DNA (transcription) and finally translation (formation of the protein on the mRNA). The steroid hormones attach to their intracellular receptors. the complex now enters the nucleus & begins transcription. RNA polymerase sequentially arranges the nucleotides to form RNA copy from the DNA. Promoters recognise RNA polymerase and thus decide which genes are to be used for mRNA creation. Enhancers play similar role but are farther away - either upstream or downstream. however, I'm not clear about the role of the cis elements. can anyone simplify?
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| mildus
Forum Guru
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That's right.
Trans elements are transcription factors.
Cis elements are parts of DNA where trans elements bind. They include: promotors, enhancers & silencers, REs (response elements for steroid hormons).
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| drk1980
Forum Guru
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great explaining mitali!
what i know of 'cis' elements(regulators) is that, they are DNA regulatory base sequences for eg promoters, enhancers, response elements etc They are located on the DNA close by to the genes and are binding sites for proteins. Some of these proteins that bind to them make up the 'trans' regulators, which are the transcription factors, namely the glucocorticoid receptor in this case.
hope this was helpful....you can refer pg71 of kaplan biochem for further explanations.
goodluck to all
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