2. 1. Gene Expression is Controlled by 3. Regulatory Proteins(调控蛋白) Gene expression is very often controlled by Extracellular Signals, which are communicated to genes by regulatory proteins: Positive requlators or activators INCREASE the transcription F>Negative regulators or repressors DECREaSE or elIMinate the transcription7 1. Gene Expression is Controlled by Regulatory Proteins (调控蛋白) Gene expression is very often controlled by Extracellular Signals, which are communicated to genes by regulatory proteins: ➢ Positive regulators or activators INCREASE the transcription ➢ Negative regulators or repressors DECREASE or ELIMINATE the transcription Principles of Transcription Regulation