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Gene Control in DevelopmentComments

Gene Control in Development

gene control in developmental biology

The development of an entire organ can be triggered by a single regulatory protein. Regulatory proteins can be either activators or repressors of transcription. Controlling activity of regulatory proteins: protein synthesis; ligand binding; protein phosphorylation; addition of second subunit; unmasking. Regulatory genes are activated or inhibited by external signals (signal transduction). Synergy: the whole is greater than the sum of the individual parts. One gene activator protein results in 1 unit of transcription, while four gene activator proteins can result in 500 units of transcription. Combinatorial actions of regulatory proteins refer to how two proteins may bind to two binding sites, and then the activator or repressor binds those binding proteins.

How Are Patterns of Gene Expression Maintained?

FeedbackFeedback mechanisms (negative/positive)
DNA ModificationDNA methylation -- chromatin compaction
Localizationlocalizing mRNAs to specific regions of the cytoplasm -- direct transport on cytoskeleton; random diffusion and trapping; generalized degradation in conjunction with localized protection
TranslationProteins that bind to the 3' UTRs of mRNA can block translation (such as preventing polyA Binding Protein from binding to the adjacent polyA tail)
microRNASmall noncoding RNAs. Approx 4% of mammalian genome. Complementary or partially complementary to 3' UTR sequences. Inhibit translation OR promote degradation of the target mRNA.

Sequential Induction

sequential induction