BIOB11H3 Lecture 22: Bio B11 Lec 22 C15 Signal Transduction II.docx
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Bio b11 lec 22 c15 signal transduction ii (see previous lec notes for most of the stuff) Fig 15-3: signal transduction pathway consisting of protein kinases and protein phosphatases whose catalytic actions change the conformations and thus the activities of the proteins they modify. Kinase 2 is activated by protein kinase 1. Once activated, protein kinase 2 phosphorylates protein kinase 3, activating the enzyme. Protein kinase 3 then phosphorylates a transcription factor, increasing its affinity for a site on the dna. Binding of a transcription factor to the dna affects the transcription of the gene in question. Each of these activation steps in the pathway is reversed by a phosphatase. Whereas protein kinases typically work as a single subunit, many protein phosphatases contain a key regulatory subunit that helps determine substrate specificity. bind epinephrine and glucagon, contain seven membrane-spanning helices.
