CopyrightThe McGraw-Hill Companies,Inc.Permission required for reproduction or display. Chapter 11 General Transcription Factors in Eukaryotes Oscar L.Miller/SPL/Photo Researchers,Inc
Chapter 11 General Transcription Factors in Eukaryotes
Polymerases need help to find the promoters The factors that attract polymerases to their respective promoters are called general transcription factors(转录因子，TF) √General transcription factors(通用转录因子) combine with an RNA polymerase to form an open promoter complex(开放启动子复合物)ora preinnitiation complex(起始前复合物)to activate transcription Class II factors work with Pol II. 11-2
11-2 Polymerases need help to find the promoters ✓The factors that attract polymerases to their respective promoters are called general transcription factors (转录因子, TF) ✓General transcription factors (通用转录因子) combine with an RNA polymerase to form an open promoter complex (开放启动子复合物) or a preinnitiation complex (起始前复合物) to activate transcription ✓Class II factors work with Pol II
11.1 Class lI Factors General transcription factors combine with RNA polymerase to form a preinitiation complex -This complex is able to initiate transcription when nucleotides are available -Tight binding involves formation of an open promoter complex with DNA at transcription start site melted While the class ll complex is quite involved, explore it first,then those of classes I and 川 11-3
11-3 11.1 Class II Factors ✓General transcription factors combine with RNA polymerase to form a preinitiation complex – This complex is able to initiate transcription when nucleotides are available – Tight binding involves formation of an open promoter complex with DNA at transcription start site melted ✓While the class II complex is quite involved, explore it first, then those of classes I and III
The Class ll Preinitiation Complex Class ll preinitiation complex contains: -Polymerase ll -6 general transcription factors: 。TFIIA ·TFIIB ·TFIID ·TFIIE ·TFIH The transcription factors (TF)and polymerase bind the preinitiation complex in a specific order 11-4
11-4 The Class II Preinitiation Complex ✓Class II preinitiation complex contains: – Polymerase II – 6 general transcription factors: • TFIIA • TFIIB • TFIID • TFIIE • TFIIH ✓The transcription factors (TF) and polymerase bind the preinitiation complex in a specific order
Class II preinitiation complex Preinitiation complex is assembled in a precise order,and forming four Distinct Preinitiation Complexes in the process. D→DA→DAB→DAB-PolF→DAB-PolF-EH Copyright The McGraw-Hill Companies,Inc.Permission required for reproduction or display. Pol II Pol Il DABPolF: DAB: Pol II TATA -5 TATA
11-5 Class II preinitiation complex Preinitiation complex is assembled in a precise order, and forming four Distinct Preinitiation Complexes in the process. D DA DAB DAB-PolF DAB-PolF-EH ➢Last the TFIIE then TFIIH bind to form the complete preinitiation complex = DABPolFEH ➢In vitro the participation of TFIIA seems to be optional ➢TFIID with help from TFIIA binds to the TATA box forming the DA complex ➢TFIIB binds next generating the DAB complex ➢TFIIF helps RNA polymerase bind to a region from -34 to +17, now it is DABPolF complex