Biology 2382B Lecture Notes - Lecture 8: Dna Repair, Spindle Checkpoint, Tumor Suppressor Gene
9 Feb 2018
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Start or restriction point regulation by rb protein. Initially identified as the gene mutated in retinoblastoma, a childhood cancer of the retina: subsequent studies found rb to be inactivated in many cancers. E2f transcription factor complex: transcription factor that promotes the transcription of g1/s phase cyclins and many other genes whose function is required for s phase. Rb usually (under conditions which do not promote cell growth) prevents expression of cyclins. Through stimulation by certain growth factors and phosphorylation, rb dissociates from e2f no longer inhibiting the expression of g1/s cyclins. Cell closely monitors dna itself and the presence of dna damage. Cell monitors nutrients/environment to ensure sufficient resources to produce two healthy cells also in checkpoints (s phase check point) Dna damage checkpoint p53 activates the transcription of p21 (a cdk inhibitor protein, cki) p21 inhibits all cyclin-cdk complexes and halts cell cycle. Dna damage leads to phosphorylation and stabilization of p53 (a transcription factor)
